Israel has developed a new 500 pound (227 kg) penetrator bomb, the MPR-500. The MPR-500 can smash through more than a meter (39 inches) of concrete, or four 200mm (8 inch) concrete barriers (floors or bunker walls) and then detonate. When the MPR-500 explodes, it releases 26,000 fragments, which will wound or kill out to 100 meters.
While the MPR-500 is an unguided bomb, it is most useful when mated with a guidance kit to become a smart bomb. The most common such kit is the American JDAM, which converts 500, 1,000 (455 kg) and 2,000 (910 kg) pound unguided bombs into highly accurate guided “smart bombs”.
Currently, most penetrator bombs are heavier (910 kg), and models like the BLU-109 can penetrate five meters (16 feet) of concrete. The heavier (5,000 pound) GBU-28 can penetrate 32 meters (100 feet) of earth, or six meters (20 feet) of concrete. Israel already has hundreds of these larger penetrator bombs, but apparently sees a need for smaller penetrators. More of the smaller bombs can be carried on each sortie. There are smaller penetrators as well.
Learn more here.
Source: Strategy Page