Check the listing for details. 6-9-13-21inch Retractable Rifle Bipod Adjustable and Foldable with Spring Return. Color: Black, Condition: New. Listed at 23.99 USD. Made of hardened steel and high grade aluminum, fine blake anodized finished. Heavy duty and light weight. Bipod for sling stud: Easy attach to or detach from the rifle with Sling Stud or Adapter,which you can select from our Store as accessory such as 20mm Adapter for Picatinny or Weaver rail， 11mm Adapter, etc. Foldable arms with spring. Shockproof and keep your rifle stable in different enviroment with Rubber foot pad. Quickly attach to or detach from the rifle using existing swivel stud. Legs can be folded forward or backward with Swing-able design for leveling on uneven ground. Length Choice : 6-9 inch / 9-13 inch / 13-21 inch ( Choose carefully ) 6-9‘’ inch / Leg Levels : 5 settings Leg Height： 6" / 152 mm (retracted) ； 9" / 225 mm (fully extended） 9-13‘’ inch / Leg Levels : 10 settings Leg Height： 9" / 225 mm (retracted) ； 13" / 330 mm (fully extended） 13-21‘’ inch / Leg Levels : 13 settings Leg Height：: 13 inches/ 330 mm (retracted)----20.5 inches / 520 mm (fully extended) 20mm adapter : 6-9 inch : 9-13 inch : 13-21 inch :