UL94 HB: The Lowest Flame Retardant Grade In UL94 And CSA C22.2 No 0.17 Standards. For Samples 3 To 13 Mm Thick, The Burning Rate Is Required To Be Less Than 40 Mm Per Minute; For Samples Less Than 3 Mm Thick, The Combustion Rate Is Less Than 70 Mm/min; Or Extinguish Before The 100mm Mark
UL94 V2: after two 10 second combustion tests on the sample, the flame goes out within 60 seconds. Combustibles can fall
UL94  V1: after two 10 second combustion tests on the sample, the flame goes out within 60 seconds. No combustibles shall fall
UL94  V0: after two 10 second combustion tests on the sample, the flame goes out within 30 seconds. No combustibles shall fall