Custom Air filter rack plenum,for filter 20x16x1",and 4 round collars 6"diameter

Description

Other pictures are just for reference.
This is a Custom  Sheet Metal return air filter rack plenum for filter 20 x 16 x 1".
Made in America by hand , housing 26 Gauge
. There is a 3/4" hem flange on one 20"x16" end
Outside the plenum (around the flange) has dimensions 17-3/4 x 21-3/4" and height 5-1/8"
, and the other side is fitted with an end cap with a  4 round collars 6" diameter
. Actual overall dimensions flange side for this rack 17-3/4" x 21-3/4" .
From top to bottom the plenum is 5-1/8" long and the collars measures 4" in length. There is a sliding door on the 20" side for filter access. The door can slide from ether side allowing for easy access. Filter for this plenum is 20 x 16 x 1". Filter is not included.