The invention relates to a piston, in particular, for use as a discharge and/or locking piston of a cartridge comprising a base body (25) having a lateral wall provided with sealants (14, 17) and a front-end wall having a vent (21). A locking element (18) is mounted rotatable in the vent (21), whereby a venting channel (23, 24) can be opened or closed by the relative rotation of the locking element (18) in the vent (21). Additionally, the invention relates to a cartridge configuration having such a piston.