This rubber membrane air diffuser is 1/2" MPT (male pipe threaded) and 8" long. These EPDM rubber air diffusers are incredibly strong and are ideal for pond aeration, circulation and destratisfying applications. Unlike air stones these diffusers are easy to clean, EPDM membrane cleans much better and easier than porous air stones. In testing these air diffusers produce a slightly larger air bubble than air stones which translates into less oxygen transfer into the water, so for fish holding tanks, raceways, fish production ponds, etc. we recommend using air stones. These diffusers are an excellent choice for pond and water garden aeration since they actually produce more circulation and water movement.