Rotational force transmitting part

摘要

An electrophotographic photosensitive drum unit includes a cylinder having a photosensitive layer at an outer periphery thereof. A drum flange is provided at one end of the cylinder, with the drum flange including a plurality of projections provided inside of the drum flange and projected radially inwardly of the drum flange, and with a space diametrically between the projections. A radially inner part of each projection has an overhang.