HARCO 109-020 2" Gasketed Knock-On PVC Pressure Repair Coupling - The Harco "Knock-On" repair coupling is the best repair coupling available on the market today. Harco's unique gasket design allows for travel in both directions, making it as easy to slide the coupling back onto the existing pipe as it was to slide it onto the repair section. The square face bell design allows for a larger object, such as a bar or wood block, to be placed against the fitting in order to knock the repair coupling into place. With no bolts, nothing to tighten to engage the gasket, no glue and no set time before backfilling can begin, the repair coupling is completed as soon as it is installed.