Length:Length is measured from the outside edge of end cap to end cap, not including any handles, threads or slip fittings. 9-3/4"
Bottom:This is the actual inside hole diameter, excluding any taper.1-7/8" Open Slotted
Premium replacement for:Unicel:Unicel part numbers either start with a "C" or contain a "CH" like "C-8475RA" or "6CH-49".C-4402
Pleatco:Pleatco part numbers start with a "P" like "PWW100ST".PAQ25N
Filbur:Filbur part numbers start with an "FC-" like "FC-0360".FC-3071
Overall, filter seemed like a good quality product, but the hole size is slightly larger than advertised. Thus, it won't stay in place with the connection in my hot tub. Fix your description.