The Ultra-High Explosive is an explosive material that explodes with even greater force than conventional high explosives. The explosive shock front from these explosives is an order of magnitude greater than conventional high explosives. TNT, the conventional method for measuring explosive power, has an ESF detonation rate of approximately 5.8 km/s (19000 feet per second), an Ultra-High Explosive charge of similar weight and dimensions reaches an astounding 57.9 km/s (190000 feet per second). The explosives are utterly destructive and are only available to the military and can only be used in the civilian world for very select applications such as mountain and mine blasting.
Ultra-High Explosives have reached nuclear weapon yields with the most powerful of them reaching in excess of 1MT (1000000 tons) of explosive power. However a 100kt Ultra-High explosive bomb is very impractical and was used for test purposes, it isn't ruled out in warfare. Since the weapon is non-nuclear, it is perfectly legal in a vast majority of instances. Despite this, nuclear weapons are still vastly more powerful. Ultra-High explosives are the most powerful non-nuclear explosives that can be created.
Ultra-High explosives are generally created the same way as High explosives, but there is a change in the explosive composition using highly volatile and explosive chemicals to boost the explosive yield. Ultra-High Explosives are found in everything from anti-vehicle and bunker-busting hand grenades to anti-tank missiles to artillery and standalone missile munitions.