This is a tenting case for the Iris. This case is designed for 3/32 silicon feet on the underside of the PCB. 

Uses standard 3mm hardware. You'll need four (4) bolts (I recommend thumbscrews) 16mm long, four (4) nuts, and eight (8) 5mm diameter magnets for each half. 

You'll need to get the pro micro as close as you can to the PCB. There is ~0.25" between the bottom of the pcb and the case.
I recommend peel-a-way sockets, available at keeb.io, but the cheapest way to do this is remove the black plastic from the pin headers that came in your kit.
Be sure to trim switch legs under the micro and use a piece of tape for electrical insulation.

The hat and magnets will need to be glued in place. The switchplate has provisions to add some adhesive to the locating pins on the hat from the underside.
Attach the hat to the switchplate before you solder any switches onto your pcb.

To improve traction, wrap a #30 rubber band around each leg lengthwise. Compatible with Ergodox EZ legs as well.

Model units are mm.

https://a360.co/2swS4hT