The Circle Hole Cutter makes installing your boat vents fast and easy. Simply place the cutter in the position on the canvas where your boat vent is going to sit, press down, and rotate the handle clockwise. It only takes one complete revolution and you have the perfect 2 1/4" hole for your boat vent. Using the circle cutter will not only save you time, but will prevent you from making costly mistakes. This one of a kind devise guarantee's cutting at least 2500 holes without dulling and the blade is replaceable. You can use this circle cutter with Boat Vent II and Boat Vent 3 just by switching the blade around.