The JLG Platform HELAC Actuator is a hydraulically driven rotator used on various JLG Mobile Elevated Work Platforms (MEWPs) to control the horizontal rotation of the MEWP platform. The actuator comes with a dual counter balance valve block mount on the front (Hydraulic fittings sold separately). For use on models: 450A, 450AJ, EC450AJ, 520AJ, EC520AJ, EC600SJ, EC600SJP, H600SJ, H600SJP, M600J. Please verify the proper part number for your machine's serial number range.