Find it here - https://doublemdefense.com/product/global-ordnance-utg-1913-rail-adapter-for-stribog/

Global Ordnance UTG Pro 1913 Stribog Backplate.

1913 picatinny rail adapter for the Grand Power Stribog, manufactured for Global Ordnance by UTG Pro in the USA.

This 1913 rail adapter Allows users to attach any 1913 picatinny brace, stocks or accessories.