Length:Length is measured from the outside edge of end cap to end cap, not including any handles, threads or slip fittings. 21-5/16"
Top:This is the actual inside hole diameter, excluding any taper.2-1/8" Open
Bottom:This is the actual inside hole diameter, excluding any taper.2-1/8" Open
Premium replacement for:Unicel:Unicel part numbers either start with a "C" or contain a "CH" like "C-8475RA" or "6CH-49".C-5396
Pleatco:Pleatco part numbers start with a "P" like "PWW100ST".PCST80
Filbur:Filbur part numbers start with an "FC-" like "FC-0360".FC-2975
All good, easy to install as well
It works great and great price!