Marvel Engineering Company
2085 North Hawthorne
Melrose Park, Illinois 60160-1173
T type TT-II 321 series are used in flow rates to 75 gpm  (3001/Min)
return lines, for a quick and easy change of cartridge. T-type filters with
threaded housings and bolt on port adapters. 300 PSIG (20.7 Bars)
T Type Threaded Housing Filters
Phone 708-343-4090
Fax 708-343-4159
T type TT-I I 321 series

Please use the above link to a PDF catalog for theses items.

TT-II 321 flows to 75 gpm and 300 psi.    T type filters with threaded housings and bolt on port adapters.