Recknagel Winchester XPR Picatinny Rail SAThe front and back weaver bases are an alternative to a full picatinny weaver rail, reducing weight and creating a space between where the rings and bases attach to the rifle. This allows for large scope mid sections and allows your scope to sit lower and to get a closer fit to the barrel. The ideal scope position is as close to the barrel as possible. Material: black anodised aluminium.