These are Professional bar adapters from Cannon. These bar adapters allows you to run 12mm Stihl mount chainsaw bars on many Husqvarna chainsaws. Great for those operators who run both brands of saws, because you only need one type of bar now, one with a 12mm Stihl mount. This adapter works best with Cannon chainsaw bars because the 12mm Stihl mount is machined longer than OEM Stihl and Oregon bars, which gives you more adjustment room. This bar plate adapter will fits saws with 9mm studs approximately 1-3/4" (44mm) apart. Please check your saw before ordering. Important Note: Not all bar mounts are manufactured the same. Some bars may require adjuster holes to be slightly enlarged for bar adjuster tab to fit.