This is well made and was the right tool for the job (made in Taiwan). The drive square doesn't have recesses for a detent ball but it fit my ratchets securely. Also, the pins go all the way through the puck without protruding out of the back and it seems that they have adhesive where they attach to the puck.
I had to deal with a stiff rear brake caliper piston on a 2011 Honda CR-Z. It took me hours and a lot of effort, using the wrong tools, to unsuccessfully make room for new brake pads. I had to reinstall the old ones (which I was fortunate to be able to).
After I got this tool. It took me less than a minute to turn the caliper piston and make room for the new pads. Make sure it's the right size for the car you want to use it on but I fully recommend it.
Measurements:
O.D. of puck = 28.5mm / 1 1/8"
Thickness of puck = 13mm / 1/2"
Thickness of pins = 4mm / 5/32" (~1/8")
Outer edge spacing of pins = 24mm / 15/16"
Inner edge spacing of pins = 16mm / 5/8"
Height of pins = 2.5mm / 3/32" (~1/16" - ~1/8")