Push in Joiner - 8mm x 8mm Quick Overview We make all our push in fittings to suit 8mm (5/16) outside diameter (OD) beer and gas line. These push in fittings are suitable to be used up to 100 psi. They are extremely easy to use and allow you to simply push your beer and gas line straight into these fittings. No need to purchase clamps. To remove the fitting simply push in the collet and the hose can be removed.