Hardener For P.38/P.40 Sachet 20g - U-POL H3840/S, U-Pol Hardener For P.38/P.40 is an additional BPO hardener for polyester body fillers. Can be used with all the U-POL and ISOPON polyester fillers.U-Pol Hardener For P.38/P.40 Sachet 20g. U-POL H3840/S Hardener For P.38/P.40 Sachet 20g