A3 Industries MFS stocks are designed for firearms that already have a rear Picatinny rail. The A3 Industries hinge can be mounted to fold left or right, and latches in both the open and closed positions. The offset extensions allow the user to configure their stock in 4 different setups as shown in the appropriate product images. This allows the user to raise or lower their cheek rest, avoid obstacles like side charging handles or ejection ports, and raise or lower the buttplate. All components are machined from aluminum and anodized low-gloss black. FeaturesPicatinny (1913) mount - sure-lok folding hinge with button latch, and quick-deployment featureHinges can fold right or leftHinges latch in both folded and open position