This O-ring replaces a worn one in gear boxes and Minimatic Unloaders from AR North America. Compatible with gear box models 1689, 1690, 1697, 1698, and 1670 and Minimatic Unloader models 4/B, VR 3/B, and VR 35. Measures 14 mm in diameter with a thickness of 1.78 mm. An OEM replacement part from AR North America.