You need to order the 21700 tube as an extra but in fact this light looks and works best with it. It should be pretty good in heatshedding too with all those fins. It looks like it houses a 22mm driver.
Edit: beaten by BSM 
You need to order the 21700 tube as an extra but in fact this light looks and works best with it. It should be pretty good in heatshedding too with all those fins. It looks like it houses a 22mm driver.
Edit: beaten by BSM