Return air plenum for filter 25x16x1 and round 12 collar, hvac duct

There is a sliding door on the 16 side for filter access. The door can slide from ether side allowing for easy access. Filter for this plenum is 25 x 16 x 1. Riveting, versus spot welding, provides a more durable bond resulting in a longer lasting rigid part that will serve you for decades.