The Clamp-On Double-Sided Chain Keeper is designed to maintain your chain on an Over/Under Idler. The double-sided and single-sided Clamp-On Chain Keepers are TerraCycle exclusive products. Nowhere else will you find a chain keeper that clamps onto the head of an idler bolt. Clamping on means freedom to float your chain keeper side to side with the chain and the idler, and it means super easy setup and maintenance. The abrasion resistant nylon arm, stainless steel fasteners and high quality machined aluminum means your Clamp-On Double-Sided Chain Keeper will be with you a long time.