Cartridge and member used for cartridge

The invention relates to a cartridge and a member used for the cartridge. The cartridge includes a developer carrying member and a developing container for supporting the developer carrying member. A development container includes a positioning portion and a rotation stop portion engaged with and guided by a guide of an image forming apparatus, and a longitudinal positioning portion, at one end in an axial direction of a developer carrying member. In a state where a cartridge is attached to the image forming apparatus, when a cross-sectional positioning range is defined by using a width, having one end at a point at which the rotation stop portion contacts the guide and another end at a point at which the positioning portion contacts the guide in an attachment direction of the cartridge, and a height being a width of the guide at the point at which the rotation stop portion contacts the guide or the point at which the positioning portion contacts the guide, the longitudinal positioning portion overlaps the cross-sectional positioning range in a longitudinal direction.