10" x 54" Poly-glass Tank, with standard 2.5" x 8 NPT top opening w/Base. Plus 1 1/4 inch Dome hole and plug for refilling tank. Normally used with 1.5 cu. ft. of media and 20 lbs. Gravel at the bottom.
Most common use is for Acid Neutralizing filters. Access hole makes it easy to add Calcite or Corosex as needed, without removing control valve from the tank.