Includes M2 replacement knob and wire lace for easy lace system replacement in the field. For use with our Headwaters® Boa® and RiverTek® Boa Boot in Vibram® and felt. For 1st generation RiverTek Boa wading boots, order M3 Boa Field Repair Kit. For the G4 Boa Boot, order the G4 Boa Replacement Kit. To verify which RiverTek Boa Boot you have, look inside the boot on the tongue label where the size is marked. 2nd Generation boots will state Boa M2 Reel and the lace length, 1st Generation boots state only Boa and lace length.