Luth-AR Roth Thumbscrew with QD Black. The QD Thumbscrew replaces either one of the standard thumbscrews and accepts the Grovtec Quick Detach sling swivel. The thumbscrew will not loosen with the QD attached. The thumbscrew is used to attach the Cheek Piece or Adjustable Butt Plate to an MBA Buttstock frame. Specifications for Luth-AR Roth Thumbscrew w/ QD: Manufacturer: Luth-AR Color: Black Additional Features: with QD Weight: 0.9 oz Package Contents: Luth-AR Roth Thumbscrew w/ QD Luth-AR TS-Roth: Roth Thumbscrew with QD Black