Cut threads in PG thread sizes commonly used for European conduit. Made of high-speed steel, these taps are for use on most metal and plastic. The square shank is compatible with tap wrenches and tap holders for drill presses and milling machines. All have a plug chamfer with 3-5 cutting threads, so they're suitable for start-to-finish tapping. When using them to tap closed-end holes, be sure to leave sufficient space at the bottom for chips to accumulate.