The C8 Blasting Block, or C8, is essentially a grenade, and is only usable by Battle Armor. C8 can be "stuck" to enemy Mechs or Vehicles, and once attached, it cannot be removed. Once the C8 block has been placed, it runs a 3 second fuse before it explodes, causing significant damage to whatever it's stuck to. This is the single most effective tool a BA can use to bring down a much larger target. Generally, it can take 2 or 3 C8 charges to bring down most 'Mechs if correctly placed on critical components.
Each BA is equipped with 1 C8 Blasting Block by default, but up to 8 may be purchased for 2000 Cbills each.