im not sure, was the only version in the app,
if you do alot of rack or comms work the rackstudz are so much better than old bolts, i use a version with 2 screws and you lock in from the back,
you can then push hardware on from the from and secure with a single tooless stud while you get the others in place and tightened up
I will inform myself about the measurement.I have old and heavy hardware, so screws stabilize the hole rack but the rackstudz look like an interesting thing.