archwick mk13 vsr 10 hop up kammerUpgrade your sniper rifle with this precision machined CNC TDC Hop Up unit from Archwick. Made from strong, lightweight T6061T6 aluminum, this hop up unit provides significantly improved accuracy and more stable shot pattern for your VSR 10 or Archwick MK13. This hop up uses a true Top Dead Center (TDC) design, which ensures vertical and even pressure on the hop up rubber resulting in more consistent shots and better range. An external O ring centers