Device Compliance
Last updated: 12 October 2026
Safety, conformity, disposal and network information for the Send Signals Check-in Kit. If you need something that is not here, email hello@sendsignals.co.uk and we will send it.
1. What the kit is
The Send Signals Check-in Kit is a small handheld device a pupil carries, used to check in and out of school and to send a short pre-set message to staff. It has no camera and does not record sound. It is not a tracker and it is not a safeguarding device.
The device is an M5Stack StopWatch (SKU C152), manufactured by M5Stack Technology Co., Ltd, Block A10, Expo Bay South Coast, Fuhai Street, Bao’an District, Shenzhen, China. Send Signals Limited supplies it with Send Signals software and service.
Send Signals Limited is the importer of this device into the United Kingdom. Our name and address for this purpose are Send Signals Limited, 71-75 Shelton Street, Covent Garden, London, WC2H 9JQ, United Kingdom, and they appear on the packaging of every kit.
Send Signals Limited is the importer of this device into the United Kingdom. Our name and address for this purpose are Send Signals Limited, 71-75 Shelton Street, Covent Garden, London, WC2H 9JQ, United Kingdom, and they appear on the packaging of every kit.
2. Conformity
The device carries CE marking, which is accepted for products placed on the Great Britain market. A copy of the manufacturer’s EU Declaration of Conformity is supplied in the box with every kit, and is available on request.
It has been assessed by a notified body against the radio equipment rules, covering electrical safety, health including radio-frequency exposure, electromagnetic compatibility and use of the radio spectrum. Test reports covering restricted substances, waste electrical equipment and lithium cell safety are held by Send Signals and can be produced for your procurement or insurance checks.
3. Carrying the device
The device has an attachment point so your school can decide how pupils carry it. We recommend attaching it to a bag or a belt loop. Send Signals does not supply a lanyard.
If you choose to use a neck cord or lanyard, it must have a breakaway safety release, and it should not be worn around the neck by younger children. Cords should not be knotted, shortened or repaired, and any cord whose breakaway has been triggered should be replaced.
4. Safety
- The device contains a sealed rechargeable lithium-ion battery. It must not be pierced, crushed, burned or immersed.
- No charger is supplied. Charge indoors on a hard surface using a USB-C cable and a charger that meets UK safety requirements.
- Stop using any device that is swollen, cracked, very hot, or damaged after a drop, and tell us.
- Not suitable for children under 3. Supervise use by any pupil who may put objects in their mouth.
- The device should not be opened. There are no user-serviceable parts inside.
The device runs on a battery at well under 40 volts, so it does not need portable appliance testing. Where a school uses its own mains charger, that charger is covered by the school’s own equipment checks.
5. Battery and disposal
The battery is a rechargeable lithium-ion cell, 3.7 V, 450 mAh. It is sealed inside the device and is not intended to be removed by the user. At end of life it can be removed by a qualified professional after opening the enclosure with a tool, for separate recycling.
The crossed-out wheeled bin symbol on the device means it must not be put in general waste. Return devices to Send Signals, or to your local collection point for waste electrical and electronic equipment. We will take back any kit we have supplied, at no charge.
Send Signals Limited producer registration number: WEE/MM8130AA.
6. What your network needs
You do not need to set up a new network for us. The device needs one Wi-Fi network with 2.4 GHz enabled and a pre-shared key, of the kind most schools already run for printers and similar equipment.
| Requirement | Why |
|---|---|
| 2.4 GHz enabled on at least one network | The device has no 5 GHz radio. |
| WPA2-Personal or WPA3-Personal | Both are supported. Certificate-based login (802.1X) is not supported at present. |
app.sendsignals.co.uk exempt from SSL/TLS inspection | The device checks our certificate against its own stored list and will not accept a replacement, so an inspecting filter stops check-ins reaching us. |
| No captive portal on that network | There is no browser on the device, so portal terms cannot be accepted. |
| Outbound HTTPS on port 443, and time synchronisation on port 123 | Sending check-ins, and keeping the clock right. |
Devices appear on your network as sendsignals-fob- followed by six characters, and never show a pupil’s name. They connect and disconnect frequently, because the radio is switched off while the device sleeps: roughly every 30 seconds while in use, every 2 to 5 minutes through the school day, and every 30 minutes overnight.
We recommend giving the devices their own network credential rather than a staff login, so it can be changed on its own if a device is lost.
7. Reporting a problem
If a device overheats, swells, cracks, or behaves in a way that worries you, stop using it and contact us at hello@sendsignals.co.uk. We record every safety report and will tell you what we find.
8. Who we are
Send Signals Limited, registered in England & Wales (company no. 17147174), registered office 71-75 Shelton Street, Covent Garden, London, WC2H 9JQ. VAT registration GB527441102. ICO registration ZC138681.