Reinforcement program for YJ series models: Impeller adopts 5-axis CNC machining 17-4PH stainless steel, dynamic balancing grade G6.3 Shaft seal upgraded to Japan NOK double-lip structure, dust-proof and water-proof grade IP67 Including M12x1.75 extension bolt kit, adapted to Teraflex 4-inch elevated modification Adapted to OE No.: 52088401AC, passed ISO 16750 -4 vibration test (amplitude 2.5g, frequency 10-2000Hz)