Per DH pg 137 it’s a “primitive grenade” – that is basically some variation of a Molotov Cocktail.

• Half Action to light them
• Penetration: 0 (If target catches on fire then subsequent fire damage ignores armor.)
• Blast: (2) half damage for taking area damage vs. being hit with it
• You only have a chance of catching on fire if you’re hit with it.
• They have the Special trait: Unreliable
• If character carrying them experiences a fall, then roll to see if containers break.