ShiningBeam S-mini XM-L T6 LED Flashlight 400 Lumens is 1.6 oz (without battery). There are a number of inexpensive flashlights with this form factor. 1" barrel, 4" length. I use Flashlight Universal Bracket Mount Holder with Velcro - Free Shipping - DealExtreme to attach to helmet. It's quite secure and weighs in at 0.7 oz.