Made from a solid piece of aluminum these pills give you massive heat sinking without the weight of copper. The led side is milled to fit standard 20mm triple boards and is just tight enough to make the Carclo optic a finger press fit to keep dirt and lint out. The driver pocket is milled to hold a 17mm driver press fit and has a 4-40 ground wire screw hole added. They fit Surefire P60 lights and are not guaranteed to fit other p60 style lights.