The Pentek PBH-420 bag filter housing, also known as the PBH-420-1, has a one inch inlet / outlet. The Pentek PBH-420 water filter housing can be found here:
http://www.waterfilters.net/Pentek-P...ng_p_0-29.html
A full selection of available bag filters for the Pentek PBH-420 bag filter housing can be found here:
http://www.waterfilters.net/Filters/...ilter-Bags.htm
Follow the above link for parts and accessories for the Pentek PBH-420.