A hopper (20) with a bias member (21) for coacting with a catch (12) for a sliding door (11) on a cartridge (10). Catch (12) has two abutments (13,14) for abutting with bias member (21). When cartridge (10) is inserted into hopper (20), bias member (21) abuts a bottom surface (15) of abutment (13) to force sliding door (11) to open and thereby create an outlet (18). Outlet (18) is on the bottom of cartridge (10) and allows transfer of components (23) into a receiving portion (22) of hopper (20). When cartridge (10) is removed from hopper (20), bias member (21) abuts a top surface (16) of abutment (13) to force sliding door (11) to close and thereby stop the transfer of components (23).