Installation diameter: 7/8" (22mm) Easy installation: No Installation Instruction Included. Thumb Throttle Assembly Compatible with the following models: Compatible with Yamaha Raptor 350 660 700 All Years Compatible with Yamaha Bear Tracker 250 1999-2004 Compatible with Yamaha Big Bear 250 2007-2009 Compatible with Yamaha Big Bear 350 1997-1999 Compatible with Yamaha Grizzly 350: 2007-2014 Compatible with Yamaha Grizzly 600: 1998-2001