Packs and body armor are not generally a good fit. SAPI plates are curved for good ballistic reasons, but their convex outer shape means that packs, especially BIG packs, are precariously balanced against them – allowing the pack to shift and pivot on your back, even with a choking tight harness. The Mystery Ranch removable Bolstered Ventilation and Stability (BVS) System was created to lock down over your ceramic torso plate with minimum pressure on your shoulder straps. Twin Bolsters stabilize the pack on the edges of your back, allowing your SAPI plate to curve into the hollow center of the pack. The Bolsters are highly durable injection molded EVA that rebounds from any compression, and can even double as a wheel chock. Spring release buckles mount the Bolsters to the frame, and split-second removability optimizes the frame for missions where body armor isn’t needed.