A cartridge (700) for insertion into a meter comprises: a plurality of cartridge brackets (704) disposed on an inner wall (703) of the cartridge; a spindle (702) mounted so as to be rotatable within the cartridge and movable longitudinally in first and second directions within the cartridge; and a plurality of testing members (708) each arranged to be supported temporarily by at least one of the plurality of cartridge brackets, each of the testing members including) a hole (306) through which the spindle is located, the spindle having a plurality of spindle brackets (706) disposed on an outer surface thereof, each spindle bracket being movable between first and second positions.
