The EN1 The Tough One SPEC-B - your ultimate companion for extreme enduro adventures. This tire isn't just a tire; it's your key to conquering the most challenging terrains. Like the original Tough One, the SPEC-B is a premium Gummy tire, but the SPEC-B goes even deeper...literally! The SPEC-B is the same race winning compound rubber and tread pattern but isn't limited by FIM Enduro GP rules of max tread depth. The SPEC-B has a deeper tread depth than the original Tough One. A full 15mm depth, which will help riders who ride in deep mud, dirt, roots, rocks, etc. If that explains your terrain, then the SPEC-B is the gummy tire for you.