The British word 'bung' is a fancy way of saying cap in English. These delrin caps are made to fit into the loop hose ports of the KISS head when the hoses are removed. Useful for keeping contaminates out of the head when disassembled.
An o-ring allows for a smooth seal and prevents the cap from falling out while being moved, and knurled delrin grip makes them easy to remove.
Sold in pairs.