MasterRoc EQ 538 PK is a 3/8-in. Hammer-In nylon packer (drive-in port) for low pressure chemical grout injection applications?. MasterRoc EQ 538 PK is a plastic (nylon) hammer-in packer equipped with a grease type fitting. It is designed for use in low-pressure polyurethane and other chemical grout injection applications to stop water leaking. Uses: Crack injection of concrete structures Stopping or slowing water flows through fine cracks in concrete structures Injection in fine concrete cracks (thinner than hairline) Injection in previously repaired concrete cracks that need further chemical grouting Sealing storm pipe, culver joints, utility vaults and manholes Features & Benefits: Made of quality nylon One-way grease-type Zerk fitting with anti-return valve A nylon set tool included in each bag Prevent material leaking after inection Minimize concrete spall and packer moving or blowout Provide a snug fit and solid connection ? Easy install, connect, and disconnect