This is a set of standoffs to support 1.6mm and 0.62 mm thick boards. 

These were designed to work with the PCB stencil printer described here:

https://dengler-mechatronik.de/?p=560

(not my design) 

The bottom of the prints has pockets for 8mm x 2mm round Neodymium magnets. I get mine from Harbor Freight PN 67488.

These typically keep there position on the galvanize sheet metal surface while allowing you to quickly swap boards. If your doing lots of boards and they are starting to slide over time some weak double stick tape (stuff you get in the stationary aisle) under the bottom really locks them in but still allows for easy removal and repositioning.