Fits any HK variant that has a factory fixed-stock steel backplate and standard buffer (not included). Installs easily with included hardware. NOT compatible with the HK heavy buffer. Compatible models include: HK-91, HK-93, HK G3, HK-33, PTR91, SR9. Will fit Cetme backplates with some gunsmithing. Features: Adjustable for cheek weld height, length of pull, and cheek weld placement Machined aluminum adjustment dials with positive click detents Corrosion resistant stainless steel shafts Rubber recoil pad with solid aluminum core Adapter for sling/monopod mounting Reversible QD front sling mount, and rear 1.5" loop Specifications: Weight: 1.930 pounds Retracted Length: 9.375" Extended Length: 10.625" Height Adjustment: 1.80" Cheek Weld Placement Adjustment: 0.65" This item cannot be exported from the United States of America. Unfortunately this does include APO addresses due to ITAR restrictions.