Specification

What you need to know before you order.

Outside dimensions, what the light does, how the sign is driven, how it is powered and how it goes up. Every figure below comes off the product we ship you.

The sign apart: clear cover, black body with the lit ring channel, screws and suction cups.

Dimensions

Outer diameter: 130.0 mm
Depth: 27.2 mm; total thickness off the glass
Light ring: Ø ≈115 mm; around the rim of the front face
Front face: Unbroken; no visible screw, button or screen — every screw enters from behind
Finish: Matte black body, clear cover

The light

The sign has one job: telling someone at the end of a corridor what the room is doing. These are the numbers that describe it.

Colours: Green · Red · Amber
Legible from: ≈30 m; in a normally lit office corridor
Viewing angle: Wide; reads at an angle and through glass
Ring appearance: Discrete points; not a flat band — that is what carries at a distance
At power-on: Dark; it shows no colour until it knows the state
Blanking: On demand; blank the ring out of hours — state=off

Connectivity and control

The sign is a device on your own network. There is no cloud account, seat licence or vendor tenant in the path.

Network: Wi-Fi 2.4 GHz; on your own network, your own SSID
Calendar: Google Workspace, Microsoft 365; rooms map to signs once
Control: HTTP; GET /api/state?state=free|busy|away|off
Readback: GET /api/status; JSON — current state, uptime, signal
Discovery: mDNS; isbusy.local on the local network
Local UI: Built-in web page; no app, no account
Updates: Over the air; signed and verified — a failed update keeps the working version
Offline behaviour: Keeps working; holds its last state and retries the network in the background
Power cut: Remembers its state

Power

Worth being blunt about: the sign is designed to live on a USB-C cable. The battery is what lets you hang it before you have run one — and move it around for a week at a time.

Input: USB-C, 5 V
Battery: Internal, rechargeable; charges from the same port
Runtime, unplugged: ≈5 days; roughly a working week
Permanent install: On the cable; the battery stays topped up while plugged in
Charge port: Flush with the outer wall, at 6 o’clock; a standard USB-C cable seats directly

Mounting

Glass: 2 × 20 mm suction cups; keyhole slots; gravity holds the locked position
Wall: 3M VHB ring; the back face is otherwise flat
Screws: Optional; if you would rather fix it down for good — screws are not in the box
Drilling: Not required; neither the cups nor the tape asks for it — nothing happens to a partition you are renting
Moving one: Minutes; lift it off, hang it, re-map the room

In the box

Sign: 1; ready to set up
Mounting hardware: Included; suction cups and a VHB ring
Made: Türkiye

Known limits

Every product has these. Most specifications leave them out, which is exactly why they are worth reading here rather than finding out in month two.

Runtime: About five days on battery; Wi-Fi is what costs it. For a permanent install, run a cable or accept a weekly charge.
Ring uniformity: Visible scalloping; The ring is not a seamless band. That is deliberate — the discrete points are what carry down a corridor.
Network: 2.4 GHz only; It will not join a 5 GHz-only network. Most corporate networks broadcast both, but it is worth checking yours before you order.