"Shock-corded" is a better description. My originals were Underwoods, but there are Hammer's collapsible, Flambeau Mad Hunters, and I believe Stony Point has one.
The main feature is shock-corded bipod with light-weight aluminum sections that fold down into a 12-14" package, but that fully extended, forms an "x", with the very small section obove the intersection cradling the rifle and fitting into your closed fist anywhere from a foot to two feet off the ground.
You are sitting while your left hand clenches the the intersection just below your rifles forend, left elbow on your left knee (two points of contact). Your right hand is obviously on the pistol grip snugging the stock into your right shoulder (third point of contact).
This can give you a very steady rest where prone and/or a bipod is unworkable. Hope this helps.
