This holder installed into 1.31mm (0.052″) holes to facilitate the easy mounting and replacement of PP1, PP3, PP4, PP6 & PP8 pogo pins. Ideal if you’re actually using these pins for what they’re designed for, and not robot appendages! Pogo pins press fit into this holder, you may have to give them a little extra push to get them to the bottom of the holder but once they are seated they stay in place quite nicely.