These are simple brackets for mounting a Raspberry Pi board to a TV or monitor with 75mm x 75mm VESA mounting holes. They fit all full-size Pi - model 4, 3B, 3B+, 3A+, etc. except the Pi Zero.
The brackets can also be used to mount a Raspberry Pi board on a TV or monitor.
The brackets can also be used with other single board computers with a 49mm x 58mm hole pattern, such as Tinker Board, Odroid C2 or C4, Rock Pi, etc.