Some bombs are thermally protected for use on aircraft carriers. The thermally protected MK 80 series bomb was developed to increase the cookoff time and decrease the reaction of bombs when engulfed in a fuel fire. The BLU-110A/B and BLU-111A/B thermally protected bombs are identical to the MK 83 and MK 84 thermally protected bombs, respectively, with the exception of the explosive filler. The BLU series bomb bodies use PBNX-109 as explosive filler. The MK 82 and MK 83 series LDGP bombs underwent a Product Improvement Initiative (PII) which entailed filling the bomb cases with a less sensitive explosive. When so filled the MK 82 and MK 83 bombs are redesignated BLU-111/B and BLU-110/B, respectively.