DMR STS Chain Tensioner. Features: Simple Tension Seeker (STS) allows the use of a 1 speed drivetrain on a vertical drop frame Perfect for Street or Dirt Jump where simplicity and durability is key Stainless steel arm mounts to derailleur hanger and dropout Loosen bolt and swing down and back to adjust chain tension High density polyurethane pulley with sealed cartridge bearings Specs: Color: silver Weight: 115g