The 2U (3.5″ tall) EQP-1A3 is a condensed version of the 3U (5.25″ high) EQP-1A. In 1971, after 10 years of EQP-1A production and due to customer demand, Gene and Ollie rearranged controls and components to reduce the height of the popular equalizer. As indicated on the original EQP-1A3 product brochures “SAME PARTS, SAME SPECS”. The EQP-1A3 was the first product in the Pultec line that we brought back into production and has continued to be very popular. New York City’s Power Station had 24 of them in each control room! We now make them both, so you can take your pick. But be assured, they both have all that Pultec mojo that you are seeking.