Steelsoft Extra Thick Heavy Duty Dryer Vent Duct Hose 4 inch 8 Feet,Aluminum Foil Flexible Ducting Kit with 4 Clamps

how much clearance does it need to make a 90 degree turn? Space behind dryer is very close, 4-5".

I wanted to add a damper, perfect with the four clamps... would there be any issues with cutting and clamping the damper someone between ends?

Is this fire retardant

Remove clear tape from plastic ends? It seems pretty hard to catch a piece.