These chainsaw chains are NOT low kickback or reduced kickback chains. They do not have any anti-kickback bumper links and are made for persons with extraordinary cutting needs and experience and specialized training for dealing with chainsaw kickback reaction. Copperhead 5-Pack 20 chains replaces Stihl 23RS-81 / 3690 005 0081. 050 Gauge, 81 Drive Links. Requires 3/16 round file to sharpen. Full chisel, professional chainsaw chain with no anti-kickback bumper links. Made from 100% imported German Steel. Copperhead chains have high-quality chrome dipped cutters for durability and heat treated rivets to prevent stretching. Fits STIHL 026 029 MS26 MS261 MS271 MS290 MS291 Chainsaws with 20 STIHL LIGHT Bars Make sure your bar is a LIGHT. 050 gauge bar and not the standard. Thank you for supporting our small business!