This listing is for a Pack of 5 Most plumbing products are measured using BSP thread dimensions which measure 1/4 inch larger than that stated, therefore this 1/2 inch BSP x 3/8 inch BSP bush has an outside thread measuring approximately 3/4 inch and an inside thread measuring approximately 5/8 inch in diameter Used for reducing the thread diameter in a plumbing fitting It is recommended to use PTFE tape or thread jointing compound to form a water tight or gas tight seal This product is available in singles, as well as more cost effective multiples of 2 and 5 from our store