Preludes had the filters stacked on edge vertically AFTER the blower fan. They had the exact same open hole in the cowl above the blower motor. If you looked in the Prelude opening you would have seen the center of the blower fan.
CR-Z and most everything after 2001 Honda put the cabin filters BEFORE the blower fan. So now you see filter media looking in the cowl opening.
Hondas prior to about 1995 did not even have provisions for cabin air filters. The filter was the heater core or if you were up town the evaporator core for the AC was your filter.
HEPA was just a filter media option. Wasn't any additional parts and pieces.