1.1 This International Standard establishes the dimensions and associated tolerances for a series of housings for hydraulic cylinder piston seals that incorporate bearing rings. 1.2 It specifies the dimensions for a range of seal housings for cylinders of 25 to 500 mm. 1.3 It is not the intention of this International Standard to set forth details of seal design, since the manner of construction of seals varies with each manufacturer. The design and material of the seal and the incorporated bearing rings are determined by conditions such as temperature and pressure. 1.4 It applies to piston-heads that may be either assembled from a number of components or made in one piece.