JLG Parts Rotary Oil Coupling is used primarily on JLG 600 Series and 800 Series Boom MEWP(Mobile Elevated Work Platform) Machines. This Rotary Coupling is mounted between the frame and turnable and allows hydraulic fluid to flow to frame mounted valves and fuctions as the turntable rotates. Model Use: 600A, 600AJ, 600S, 600SJ, 601S, 660SJ, 680S, 800A, 800AJ, 800S, 800SJ. Please ensure proper model and serial break before parts purchase.