Length:Length is measured from the outside edge of end cap to end cap, not including any handles, threads or slip fittings. 8"
Bottom:This is the actual inside hole diameter, excluding any taper.1-15/16" Open
Premium replacement for:Unicel:Unicel part numbers either start with a "C" or contain a "CH" like "C-8475RA" or "6CH-49".C-4304
Pleatco:Pleatco part numbers start with a "P" like "PWW100ST".PC7-TC
Filbur:Filbur part numbers start with an "FC-" like "FC-0360".FC-3711
Other:WLHS2070, IMSW2070, 10505
These filters last a long time do a great job