Includes M2 replacement knob and wire lace for easy lace system replacement in the field. For use with our RiverTek Boa® Boot and RiverTek Boa® Boot - Felt. For 1st GENERATION RiverTek Boa® Boots please order M3 BOA® FIELD REPAIR KIT. For the G4 Boa® Boot, please 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.