SI-120 SnapIdle Floating Chain Tensioner (0226)SI 120 SnapIdle Floating Chain Tensioner Snapidle catalog link here For Size 120 1 Riveted or Cottered Style Roller Chain Correct operating tension is an important factor in the satisfactory performance and life of any chain drive. As chains wear they elongate, which results in sway, slap and increased vibration. This puts undue shock into the drive and increases bearing wear. As the chain elongates, it "crawls" out of the sprocket teeth and results