Use this Nylon Cap screw to protect your threaded rods or create a safety stop at the end of a rod. Knurled finish allows you to simply screw it onto the end of any rod by hand. The thread is 1/2-13 and works with all Berkey System threaded rods. It also works with other manufacturers rods that have a 1/2-13 thread. This cap screw weighs next to nothing at just 4 grams. Color is black. Quantity is one.