They're random un-branded ones I picked up from a local hardware store, and look somewhat similar to this: https://www.amazon.co.uk/blah/dp/B01N6EUXPF/ https:/

They're random un-branded ones I picked up from a local hardware store, and look somewhat similar to this: https://www.amazon.co.uk/blah/dp/B01N6EUXPF/ https://www.amazon.co.uk/blah/dp/B01N6EUXPF/ I just used some double-sided tape to stick them to the wall, about 1 foot off the ground, so I can get them off easily when I need to replace their batteries.