Shelly's new Presence Gen4 sensor, available starting today at $84.99 through the company's US online store, uses mmWave radar instead of a camera to detect the presence, motion, and activities of up to ten people and pets simultaneously — without recording anyone.

That last clause is the whole pitch. The Bulgaria-based smart home maker, which launched its $50 subscription-free security camera just last month, is betting that homeowners want occupancy sensing without the privacy baggage that comes with lenses and footage.

The device uses millimeter-wave radar to build a motion map of a room. It can sit on a shelf or table on its built-in stand, or mount permanently to a wall or ceiling. Because it never captures video, there's nothing to hack, leak, or subpoena — a selling point that's increasingly shaping how presence detection gets built into home automation.

Why does mmWave matter for smart homes?

Radar-based presence sensing solves a problem that simpler sensors can't. Passive infrared motion detectors go blind when a person stops moving — sit still at a desk, and the lights shut off around you. mmWave radar detects micro-motion: breathing, typing, a shifting posture. That makes it useful for automating heating, lighting, and security based on whether a space is actually occupied, not just whether something recently moved through it.

The Gen4's ability to track up to ten people at once, and to distinguish their movement through rooms or large open spaces, pushes it past basic occupancy triggers toward zone-level automation — hallway lights that follow you, HVAC that backs off when a room empties.

Where can you buy it?

Availability, at launch, is limited:

• Shelly's US online store carries the Presence Gen4 now at $84.99
• Amazon and Best Buy listings are expected to follow soon
• Shelf placement and permanent mounting are both supported out of the box

At $84.99, the sensor sits well above Shelly's typical bargain-bin relays and plugs, but it undercuts many competing multi-target mmWave presence sensors while adding pet detection and Shelly's native automation integration.

What comes next?

The Presence Gen4 arrives a month after Shelly's $50 camera, and the pairing is deliberate: the company now covers both halves of the home-monitoring market — customers who want video, and customers who explicitly don't. If the wider retail rollout lands at the same price, radar-based presence sensing moves one step closer to being a default smart-home building block rather than an enthusiast's add-on.