A valve, in particular for hydraulic circuits, includes a valve body (4) designed as a cartridge that can be fixed in a housing (6) having fluid connections (8) by a securing device (20, 26, 28). The securing device has at least one blocking element (20) in the form of a separate component between the valve body (4) and the housing (6). The blocking element has blocking surfaces that can be moved relative to the longitudinal axis (18) of the valve body (4) between an assembly position allowing the valve body (4) to be inserted into the housing (6) and a blocking position in which the blocking surfaces secure the valve body in an assembly position, preferably with zero backlash by bearing against retaining surfaces (26, 28) of the housing (6) and the valve body (4).