PROBLEM TO BE SOLVED: To achieve a radial sliding seal sub-assembly that exerts pretension on a sealing surface using a uniform pretension force.SOLUTION: A metering device includes a piston-cylinder instrument and a sliding seal sub-assembly (10) that seals a clearance between a cylinder (142) wall and a piston rod (28) wall. The assembly includes a sealing element (12) and a pretension element (14). The former includes a sealing section (16), and a sealing surface (18) facing in a first radial direction is formed thereon for sealing, and sliding contact in an axial direction with a working surface (144), and a pretension surface (20) facing a second radial direction is formed thereon for engagement with the element (14) for transmission of the pretension force. The metering device includes a plurality of elements (14) in the same shape arranged in an axial direction, and respective elements (14) includes a spring carrier (26) and a plurality of separately formed radial spring segments (22) supported thereon.
