A3 Industries Modular Folding Stock Picatinny 1913 Hinge Mount 6.25In Straight Extension Arm Polymer Butt-Plate With Magpul v1 Rubber Butt-Pad Black. They are available in multiple configurations to customize your stock for just about any application.The hinge can be mounted to fold left or right and latches in both the open and closed positions. The offset extension arms are available in straight or offset and in 6 different lengths. 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. Our extension arms are available in both straight or offset configurations. Straight extensions simply extend rearward positioning the stock end in line with the hinge point. Offset extensions offset one end 1.25" from center. Each end is symmetrical allowing the user to mount it in 4 different positions. These offsets can be used to clear objects such as an ejection port or charging handle raise/lower a cheek weld for different height optics or position the brace end higher or lower to suit your shooting preference. All extension arms incorporate M-LOK slots along the full length of the arm. This allows the user to mount a QD (Quick-disconnect) sling mount anywhere on the extension or any other M-LOK accessory. This also allows you to mount the A3 Clamp-on cheek rest CRU-101 or the XENO Adjustable Cheek Riser Specifications for A3 Industries Modular Folding Stock w/ Picatinny 1913 Mount: Manufacturer: A3 Industries Gun Type: Carbine Gun Make: Universal Gun Model: Universal Color: Black Hand: Ambidextrous Stock/Brace Material: 6061-T6 Aluminum Mount Type: Picatinny Fabric/Material: 6061-T6 Aluminum Attachment Type: Picatinny Package Contents: A3 Industries Modular Folding Stock w/ Picatinny 1913 Mount What firearm models does the manufacturer say A3 Industries Modular Folding Stock w/ Picatinny 1913 Mount is compatible with? The manufacturer suggests that A3 Industries Modular Folding Stock w/ Picatinny 1913 Mount is compatible with UniversalA3 Industries MFS-6-50-STR-BP3: Modular Folding Stock Picatinny 1913 Hinge Mount 6.25In Straight Extension Arm Polymer Butt-Plate With Magpul v1 Rubber Butt-Pad Black