The Standard is 2.9oz
the H is 3.6oz
and the Extra Heavy is 5.2oz
I don't know what the Double Tungsten weighs, but it should be the same as an H2.(4.4oz)
FYI...if you order the Extra Heavy from Midway USA, they will send you a DPMS H Buffer instead. Product mix up, and they don't actually stock the Extra Heavy yet. In the process of getting a refund from them now.