These files are for mounting a monopod to the Catrike Dumount seat support bar, 26mm diameter. There are 3 files, the main barrel made out of PETG that the foot of the monopod slides into, a bushing (white in the photos) made out or TPU filament. Once printing is complete I cut the bushing to allow for easy installation. Lastly the cap for the barrel, also made out of PETG. The cap is attached using two M4 x 40mm Alan head screws. No nuts are needed as the M4 will screw securely into the barrel assembly. Just be sure to start the screws in straight.