A wet electrophotographic image forming apparatus detects color per print page and executes printing by turning on only the development bias of a developing unit to be used for printing. A central control module distributes the items donated by a donor to a recipient based on a recipient’s qualification and an availability of the items. The carriages are configured to receive different needle hubs having any number of needle sizes. The short Picatinny type rail portion has a cross groove which cooperates with a cross-bolt to lock an accessory on the mount.