This is a bracket designed initially for a Tacklife Digital 150mm Caliper although it does work on many other brands/models.
I also use it on a Silverline 300mm Caliper and some other unknown branded 150mm.
The Caliper is attached using imitation 3M VHB Tape that I bought from Wish for about £1 a roll.
Width: 40mm
Height: 25mm
Thickness: 2mm
Full Depth: 12mm
Hole Depth: 8mm
Hole Width: 18mm
The author hasn't provided the model origin yet.