Ok folks, we tried to have a pin made for a certain firearm and the design did not work out as planned. - in short, the diameter was too small for the hinge pin hole in the weapon  Now, we are sitting on a ton of quick takedown pins that have a diameter of 3.75mm that can range from 3.5-3.75mm.  The working length between the detent pin and the pull ring is 23mm and that can range from 23-23.5mm.  It has a 1" takedown ring.

The pin and pull ring are stainless steel and have a black oxide finish by the way.

This is a good chance to get an oddball sized pin if you need one.