Introducing the hybrid classic! Revised with the success of the 4.0 Asterisk has introduced the 4.1. This includes all the features of the 4.0 but eliminating the liners. These liners are still available as an option. With gear getting smaller and tighter in the knee joint area, the collapsing three-piece patented patella makes tighter pants easy to maneuver. This brace is also easily repairable in the field with the part available here in the Asterisk factory in U.S.A. All Asterisk braces come with the patented Anti-Rotation Tethers. A.C.M. Frame: Anatomically correct design carbon fiber epoxy matrix. Rigid and lightweight, impact distributing structure. Asymmetri-Glide Hinge: Tracks the natural "rolling-gliding" motion of the knee joint. Asymmetrical design allows each hinge to set properly. Allows for automatic tibia alignment of lower frame.