Designed by The US and deployed between 1944 and 1948, the so nicknamed "Cloudmaker" T-12 Explosive Device, was in the "Earthquake" Class of Ordnance. Named for the massive cloud of smoke and debris caused by it's detonation. Smaller than it's English "Cousins", The T-12 could carry up to 43,000-pounds of TNT. They were 40-feet long and had a 40-inch diameter. Deployed from the larger B-29 Super Fortress Bomber, the optimal altitude for deployment was around 15,000-feet. Due to it's length, The T-12 could achieve a "drop speed" of 300-mph. Due to a hardened Case, The T-12 could penetrate 120-feet of Earth, as well as up to 29-feet of concrete. They were used with great effect against both Germany and Japan.