G Thread (British BSPP) Male to NPT Female Adapter - Lead-Free (2" x 2")Cascada Showers G Thread (British BSPP) Male to NPT Female Adapter Lead Free (2" x 2") G Thread is a Parallel (straight) thread (BSPP British Standard Pipe Parallel), which has a constant diameter. The NPT thread is slightly tapered, while the G connection is straight. No Washer is Needed. G Pipe fittings 2" Male Thread Water Pipe to NPT 2" Female Adapter. British BSPP (G) 2" Male to NPT 2" Female pipe fitting converter (Brass) "G thread male" means