Stainless Steel Straight External Threaded Pipe Nipple 1/2 BSP. This is often used to join two female BSP or NPT fittings. As it has a parallel thread (BSPP) it is perfect for attaching stainless ball valves to pots and stuff like that too. If you want to install this onto a pot you just need to drill a hole that is about 20.5mm diameter.