These are 10 high quality replacement guide bar nuts and unlike some the replacement nuts on eBay these nuts are made like the original bar nut, they are tall enough so they will not slip off your combination wrench when you are tightening the bar nut with your wrench. These 13mm bar nuts replace OEM number 503220001 and work great one Husqvarna, Jonsered, RedMax, Echo and other brands of chainsaws.