Meperfluthrin - a pyrethroid ester[7] Butylated hydroxytoluene (BHT) – an optional additive used to prevent pyrethroid from oxidizing during burning. Piperonyl butoxide (PBO) – an optional additive to improve the effectiveness of pyrethroid. N-Octyl bicycloheptene dicarboximide (MGK 264) – an optional additive to improve the effectiveness of a pyrethroid.