Designed these bumpers for the Blade Torrent 110 although it will probably fit other 1104 sized quadcopters. I used the stock screws that came with the Prop guards. I removed the prop guards. The TPU under the motor is 2 mm. If you want to keep the prop guards you will need screws that are 2mm longer. I feel it flies much better without the prop guards, especially on 3S. I printed them in TPU using 50 percent infill to give it some "give" when it hits something. If you print this and like it consider sending me a $1 tip. If not, no biggie!