Reebok 4K KFS Junior Shoulder Pads. Reebok’s 4K shoulder pads at a great price are designed for beginner to intermediate level players without sacrificing protection or comfort. As a step up from the 3K shoulder pads, Reebok has incorporated KFS (Kinetic Fit System) to the 4K’s which is a 2-piece front, and 2-piece back construction featuring aerated lightweight IXPE foam for comfort and mobility. A now hinged clavicle on the 4K’s allows for full range of motion making the shoulder pads move with the many motions of your body during play. The sternum has a PE insert and IXPE foam which is a super-lightweight construction that provides a high level of protection. Low-profile JDP shoulder and bicep caps are designed to disperse the energy of impacts away from fragile shoulder joints.