The OFD BLAK-JAK liner retention system provides a simple, compact design with easy installation and reduced weight for easier operation. There is only one HYDRA-CEL (hydraulic, tension device) to maintain rather than individual hydraulic assemblies. The redesigned LOK-CEL (tensioned, mechanical device) body and locking nut assemblies are designed in conjunction with National Oilwell Varco liner and fluid end technology. These mechanical designs are simple, rugged, and effective. The OFD BLAK-JAK Liner Retention System is available for specific NATIONAL, OILWELL, CONTINENTAL EMSCO and Gardner Denver pumps.