These stops are turned and finished off with a black oxide and oil bath, they are slightly undersized at the bottom to slip fit into 5/8" (0.625") table holes.
Use a pair of pins to quickly set up (locate) an edge on your fixture tables. Use 4 pins together to quickly create a 90 or 45 degree angle. These work great with the BuildPro Inserta Clamps available through our site here as the fastest, simplest way to setup common angles.