The Hallite 455 double acting piston seal provides a premium quality product to fit the industry standard NFPA (T3.19.18-1973) housing. It comprises a bronze filled PTFE face ring, which is pre-loaded by a square section NBR ring. The cap ring is precision machined from a compression moulded billet. The machined face ring has chamfered corners for easy installation. As only the PTFE face ring is in contact with the sliding surface, friction is very low and stick slip movement is eliminated. The housing width allows for a narrow width piston, but it is recommended that an adequate bearing be mounted on either side of the seal as shown. The Hallite 455 seal is not recommended for applications where it is necessary for the pressurized cylinder to maintain the load in a set position.