The best way to attach your flashlight to you helmet is the ALD-05 Helmet Flashlight Holder. The rubber suction cup strap securely attaches to most types of helmets. Fits flashlights with a body diameter of 20-28mm and the mount is 360 degree adjustable, allowing you to put light where you need it. Made of an anti-static rubber material, the ALD-05 is heat-resistant, oil-resistant and built to withstand any environment.