The U.S. Air Force awarded two contracts for the production of bunker buster bomb warhead bodies for up to $897 million, a U.S. Department of Defense release said.

Superior Forge and Steel Corp., Lima, Ohio, was awarded up to $476,935,075 and A. Finkl & Sons Co., Chicago, was awarded up to $419,633,500 for BLU-137/B penetrator warhead production, the Wednesday, June 27 release said.

The contracts guarantee production of 300 bodies each in the first year, and up to 3,500 bodies each in the subsequent four years. Work under both contracts is expected to be completed by May 3, 2020.

The 2,000 lb bomb is used to defeat hardened targets like bunkers and aircraft shelters.

No technical specifications for the BLU-137/B have been released, but FlightGlobal reported in 2017 that the BLU-137 is an improved and re-designated BLU-109 designed to correct deficiencies and improve the reliability of the weapon. The new warhead uses a modified Joint Direct Attack Munition tail kit and is only compatible with JDAM’s GPS/INS guidance system.

The Drive also noted that the U.S. Air Force’s 2018 budget request said that the “BLU-137 will increase fuze survivability when used against bunkers, aircraft shelters, and reinforced targets,” meaning that after the bomb penetrates the target, it is more likely that the AFX-757 explosive that fills the upgraded bomb will explode.