This is a universal filter clip for any box fan. It can be used with any 1" furnace filter. I designed it for my 20" Lasko box fan, but it will fit on any.

Print two or three clips, one for each side and an optional for the bottom. If your fan has rear facing feet, you may not need the third clip.

I used mounting tape squares to attach the clips to the fan. Filters can then be slipped in and out without effort or damage.