NOTE: according to some customers' comments, the 2 pieces Nipples were changed from 1-1/4" to 1-1/2". The longer Nipples will fit better for various faucets.Designed for simple installation. Allows installation of wall mount faucets and wall mount pre-rinses within standard backsplash space. For 1/2" NPT threads only. 1/2" pipe has interior diameter (I.D.) of 1/2". Faucet's water inlet opening is close to 3/4". NOT for home faucet with 3/8" pipes.