It's machined aluminum, and modeled after the most stylish lights of 50-60 years ago. The light part, the guts, are the same as on Soma's Road Flares, the bar-end lights. So, takes the same AAA cells, has the same on/off side button (steady and flashing), and all in all, it's the same except for the housing. It weighs 3.4oz.

You mount it on almost any unused dropout eyelet or hourglass rack mount. The mounting base flips around and it comes with the necessary simple stuff you'll need to mount it. No empty eyelets or rack bosses, or maybe your frame didn't even come with them? The Silver Bullet can deal with that, because it comes with a nice plastic clamp-on piece so you can mount it anywhere on the seat stay. Requires normal seat stays--if you have fat, aerodynamic ones, you're on your own.