Product Library / Sensors & Detectors
Research profile · last verified 2026-08-14THIRDREALITY Smart Presence Sensor R2
⚠ Similar names, different products: Third Reality's sensor shelf carries several devices a shopper will read as interchangeable and which detect completely different things: this mmWave PRESENCE sensor (radar — sees a still person), a 'USB Motion Sensor' at $14.99 (PIR — sees movement only) and a 'Vibration Sensor' at $19.99. Presence and motion are the distinction that decides whether the bathroom light stays on while you are standing still. The 'R2' is the generation marker; the model string on the SKU is P1MSR1A1-1.
Exactly which product this is[1]
- Model number
- P1MSR1A1-1
- Generation
- R2
- Region this page covers
- US
- Also sold or listed as
- THIRDREALITY Presence Sensor R2 · Smart Presence Sensor R2
“Not established” means we have not sourced that detail yet — not that the product has no model number, generation or regional variant. We publish the gap rather than filling it.
Compatibility
| Ecosystem | Support | The catch |
|---|---|---|
| Amazon Alexa | PartialPartial support — see the catch[2] | Reachable only through an Echo that has a Zigbee radio built in — the vendor's compatibility line ends with 'Echo devices with built-in Zigbee hubs', which is a small subset of Echoes. A plain Echo Dot cannot host it. Recorded partial because the route exists but depends entirely on owning the right speaker, and the vendor names no Alexa capability detail beyond hosting.In Amazon Alexa you also need: a Zigbee hub |
| Google Home | InconclusiveWe researched this and the evidence doesn't settle it — the catch explains why[3] | Google is not named anywhere on this product's page — a token search of its copy returns zero occurrences — and Zigbee gives Google no direct route. Whether a given hub re-exposes the sensor to Google Home is a fact about that hub, not about this sensor. Recorded unknown rather than none because the vendor states no refusal. |
| Apple Home | InconclusiveWe researched this and the evidence doesn't settle it — the catch explains why[3] | ⚠ THE PER-PRODUCT ASYMMETRY WORTH KNOWING: the vendor's own Smart Plug Gen2 copy names an Apple HomeKit route through its separately-sold Smart Bridge MZ1, and this sensor's page names no Apple route at all — zero occurrences of 'Apple', 'HomeKit' or 'MZ1'. Same brand, same protocol, different published answer, so the plug's bridge path must not be read across to this sensor. Recorded unknown: no vendor statement either way. |
| SmartThings | WorksWorks with this ecosystem[2] | Named directly by the vendor among its supported platforms, alongside Aeotec — which matters because Aeotec builds the SmartThings hub hardware. Requires a hub with a Zigbee radio; presence and absence are exposed as automation triggers.In SmartThings you also need: a Zigbee hub |
| Home Assistant | WorksWorks with this ecosystem[2] | The route the vendor documents in most detail, naming the stacks rather than the brand: 'Home Assistant (ZHA or Zigbee2MQTT)'. A standard Zigbee 3.0 device on a local coordinator — no vendor cloud in the path, and the five sensitivity levels are exposed as device settings on a Zigbee coordinator rather than locked in a vendor app.In Home Assistant you also need: a Zigbee hub |
? Inconclusive means we researched that ecosystem and the evidence doesn’t settle it — the catch says why, and the sources are listed below. It is a statement about the available evidence, never a verdict on the product. A Setup Check researches your exact setup where the official sources don’t answer.
Protocols: ZIGBEE[2]
Needs before it works: A Zigbee hub or coordinator is REQUIRED — the vendor states 'Requires a compatible Zigbee hub or coordinator' and names the platforms it supports: 'Home Assistant (ZHA or Zigbee2MQTT), SmartThings, Aeotec, Homey, Hubitat, and Echo devices with built-in Zigbee hubs'. There is no direct-to-phone or Wi-Fi mode.[2]
What it can do[5]
You can tell it to
Not established — we could not confirm this from vendor documentation
It reports
- Presence detected
Listed capabilities are what we could establish from vendor documentation. An ability missing here is unestablished — not necessarily absent.
Subscription reality[2]
✓ Works without a subscription: Yes.
Vendor account required: Not established — we have not sourced this yet.
No subscription, plan or fee appears anywhere in the vendor's copy. A Zigbee sensor has no vendor cloud in its path once a hub adopts it; any recurring cost belongs to the hub's ecosystem rather than to this device.
Maintenance reality[2]
- Batteries: 3 × AA — expect roughly 36 months per set
- Works without the internet: Not established — we have not sourced this yet. It does not mean the product fails without the internet.
- The vendor quotes '3 AA batteries, up to 3 years in typical usage' — an unusually long claim for a radar sensor, and the reason this one can go where no outlet exists ('hallways, bathrooms, cabinets, storage rooms, and other areas where wired power is inconvenient'). Detection is 24 GHz mmWave radar with five sensitivity levels and a stated range of roughly 1 to 5 metres; the vendor says it detects 'through common non-metallic materials such as wood and glass' and stays stable 'across changes in light, temperature, and humidity'. ⚠ It also publishes its own false-positive limit rather than hiding it: 'Environment learning helps reduce false triggers from everyday background movement, such as airflow or slight curtain movement. Strong or repetitive motion, such as fans, may still trigger detection.' In the box: the sensor and three AA batteries.
- Security updates: THIRDREALITY publishes no security-update support date for this model. That is a gap in what the manufacturer has published, not evidence either way — some makers declare a support period and some say nothing at all.[2]
The catch
Two things decide whether this $39.99 sensor is a bargain or a brick. First, it needs a Zigbee hub — no Wi-Fi, no direct phone pairing — and the vendor's list of what qualifies is specific: Home Assistant (ZHA or Zigbee2MQTT), SmartThings, Aeotec, Homey, Hubitat, or an Echo that has Zigbee built in. Second, it is a radar sensor and radar has a characteristic failure the vendor publishes rather than hides: 'Strong or repetitive motion, such as fans, may still trigger detection.' Point it at a ceiling fan and it will see a person forever. What you get for the money is genuinely useful — presence rather than motion, so a light stays on while you sit still, through a cabinet door or a pane of glass, on three AA batteries the vendor rates for up to three years.
Who it's for
A Home Assistant, SmartThings or Hubitat household adding presence detection to rooms where people sit still and PIR sensors turn the lights off on them — bathrooms, offices, reading chairs — and that can place it away from fans and airflow. It is not for anyone without a Zigbee hub, and not for an Apple Home household: unlike this brand's plug, the sensor's page names no Apple route at all.
Sources & method
Numbered sources below back the facts marked with the matching number above. This is a research profile: compiled from manufacturer documentation, certification registries, and published testing — we state facts, not verdicts, and we have not physically tested this unit. How we work →
- [1] https://www.3reality.com/products.json (301-redirects to thirdreality.com; read 2026-08-14) — product 'Smart Presence Sensor R2', product_type 'Smart Sensors', tag 'Zigbee', published 2026-05-09, single variant SKU P1MSR1A1-1 at price 39.99 with compare_at_price 39.99 (not a discount), available: true. — vendor structured-endpoint read (Shopify products.json), verified 2026-08-14Backs: Product identity, Price, Market availability
- [2] https://www.thirdreality.com/products/smart-presence-sensor-r2 (read 2026-08-14) — 'Zigbee 3.0 connection: Requires a compatible Zigbee hub or coordinator. Supports platforms such as Home Assistant (ZHA or Zigbee2MQTT), SmartThings, Aeotec, Homey, Hubitat, and Echo devices with built-in Zigbee hubs.' Specifications block: 'Protocol Zigbee 3.0', 'Detection technology 24 GHz mmWave radar', 'Power 3 AA batteries', 'Sensitivity 5 adjustable levels', 'Hub requirement Compatible Zigbee hub or coordinator required', 'Package includes Smart Presence Sensor R2 × 1, AA batteries × 3'; battery life '3 AA batteries, up to 3 years in typical usage'; detection range stated as 1 to 5 metres. Behaviour claims verbatim: 'Detects presence through common non-metallic materials such as wood and glass, and remains stable across changes in light, temperature, and humidity' and 'Environment learning helps reduce false triggers from everyday background movement, such as airflow or slight curtain movement. Strong or repetitive motion, such as fans, may still trigger detection.' Zigbee is the only radio published. No subscription, fee, warranty term or OTA-update claim appears in the copy. — vendor-page research, verified 2026-08-14Backs: Protocols, Required hub or bridge, Power source, Installation, Maintenance, Subscription, Security-update support period, Amazon Alexa compatibility, SmartThings compatibility, Home Assistant compatibility
- [3] The product's copy was searched by TOKEN rather than by topic on 2026-08-14 (method note 81): 'Apple' 0 · 'HomeKit' 0 · 'Matter' 0 · 'MZ1' 0 · 'Google' 0 · 'Alexa' 0. The Alexa route recorded on this record comes from the compatibility sentence's 'Echo devices with built-in Zigbee hubs' rather than from the word Alexa. ⚠ The Apple absence is informative BECAUSE the same vendor states the opposite one product over: the Smart Plug Gen2's copy reads 'Enabled by Smart Bridge MZ1 (Sold Separately), integrates with Apple HomeKit, Google Home, Amazon Alexa (Smart Speaker required) and SmartThings'. Two products, one brand, one protocol, different published answers — so neither cell is filled from the other, and both stay 'unknown' here because absence is not denial. — vendor-page research (token-exhaustive absence sweep; sibling product read for contrast), verified 2026-08-14Backs: Apple Home compatibility, Google Home compatibility
- [4] Listed and available on the vendor's own storefront on 2026-08-14 (published 2026-05-09, one of the newer items in the range) with a live product page. Nothing marks it end-of-life. Researched 2026-08-14 from THIRDREALITY's own storefront and product page only; no third-party retailer or review site was used as evidence. Gaps stated rather than filled: appPlatforms null, accountRequired unknown, localOperation unknown — a Zigbee sensor's account and local-control story belongs to the hub that adopts it, and the vendor claims nothing about either. — vendor research — new record, verified 2026-08-14Backs: Service status, Research status
- [5] thirdreality.com product page for the Smart Presence Sensor R2, read 2026-08-20: the sensor provides "presence or absence as a trigger for lights, thermostats, curtains, security cameras, and mobile alerts in compatible smart home systems", with "Accurate human presence detection, including stationary and micro-motion". Platform scope: "Supports platforms such as Home Assistant (ZHA or Zigbee2MQTT), SmartThings, Aeotec, Homey, Hubitat, and Echo devices with built-in Zigbee hubs." — vendor-and-ecosystem-doc research (BQ-187 capabilities population, batch 8 — sensors + garage-access), verified 2026-08-20Backs: Capabilities
Compatibility and lifecycle information reflects the last-verified date above and can change without notice (firmware updates, cloud-service changes, discontinuations). It is provided as-is, for information — verify with the manufacturer before purchasing. Spot an error? Tell us and we'll fix it. Full terms: Terms of Service.