4251: Conforms with EN 405 FFA1P1. APGY: Particulates 4 x OEL, Organic Vapour 10 x OEL. 4255: Conforms with EN 405 FFA2P2SL. APF: Particulates 12 x OEL, Organic Vapour 10 x OEL. 4277: Conforms with EN 405 FFABE1P2SL. APF: Particulates 12 x OEL, organic vapour 10 x OEL, inorganic 10 x OEL, acid gases 10 x OEL. 4279: Conforms with EN 405 ABEK1P2. APF: Particulates 10 x OEL, organic vapour 10 x OEL, inorganic 10 x OEL, acid gases 10 x OEL, ammonia 10 x OEL.