These are black oxide coated steel slotted posts designed to fit MRDs. They are used for mounting sheath and holster attachments. Because they are slotted, they can be easily tightened or removed. Some users also like to reverse their mountings to make the attachment more secure. These will fit any screw with an 8-32 thread.
Black Oxide Coated
.500 barrel length (under head)
.1925 barrel diameter
.400 head diameter