The CSR Precision Picatinny buttstock adapter will mate a wide variety of 1913 Picatinny/STANAG 4694 NATO mounted buttstocks to your SIG SG550, SG551, SG552, SG553, SG556 or SG522. You can now configure your rifle to you very own needs.
The adapter is CNC machined from aerospace grade aluminium and mil-spec type III class 2 anodized matte black.