These Retro-fit vent plugs are used after the Epoxy surfboard has been completed. They provide a spot for the board to vent air and gases. To release the gas/air simply unscrew the thumbscrew and wait 5 minutes. To install vent plug use a 5/8″ hole saw bit to drill a hole through the fiberglass of the completed surfboard. Then mix some 5 min epoxy and spread it around the collar and a little on the shaft, then press the plug in and you’re done!