Excellent hadn’t even thought of screwing them in.
I install mine external on top of the tents. Sew one end of the prefilter closed. Put prefilter in the carbon filter. Pull open end through carbon filter flange and push carbon/prefilter on the discharge side of the fan housing and toss on top of tent. If I need to clean the whole exhaust fan assembly I pull the flex duct out of the tent and unplug it. Take the whole unit outside, disassemble unit, blow it out with compressed air and a brush and reassemble. Keep extra prefilters on hand and keep them laundered and air dried. No fuss, muss or BS messing with the fans and filters. No hanging, messing with lights and all of the inside tent height. Plus the added benefit of a much more efficient fan. You lose 50% of your possible cfm and fan pressure by making a fan suck through filter media instead of loading proper and blowing through filter media.