This is a holder for the KK 2.1's buzzer that uses the arm mounting hardware. The screw hole is countersunk to only be 1 mm deep, so you shouldn't need to use longer screws than what already comes with the frame. This part was designed for a Neewer brand F450 frame, and hasn't been tested on frames from other manufacturers. Some adjustment may be required. The buzzer should fit tightly in the opening, but a few drops of glue can be used if it's lose.