#SK220 III,SK220LC III,SK220 IV,SK220LC IV Boom LH Cylinder#2438U1136F1. KOBELCO Seal Kit for. #SK250 IV Boom LH Cylinder#2438U1136F1. #SK250 IV Boom RH Cylinder#2438U1135F1. #SK250LC IV Boom LH Cylinder#2438U1136F1.