This is an enclosure for a sonoff IoT switch. The enclosure provides a means of protecting the device and enhances cable strain relief if used in conjunction with cable ties and the holes at the rear of the enclosure. The lid is vented, and the holes allow LED status to be viewed, it's got a lip, and can be secured with countersunk screws (and/or cable ties). The enclosure is large enough to house the device and eg an external by-pass earth lead.

The suitability of this enclosure is fine for my application, but you may need a different/better one for your application. Electricity is dangerous, seek professional advice if unsure about anything.

The photographs are of a previous version of this enclosure. I have rounded both the lid and the box corners, and the vent holes in the lid are smaller and more numerous than than those in the photograph.