CZ-USA 11356 Scorpion 20rd 9mmLuger Black Polymer
https://www.tandktactical.com/shop/806703113562-cz-usa-11356-scorpion-20rd-9mmluger-black-polymer-16856
https://www.tandktactical.com/web/image/product.template/16856/image_1920?unique=1304c0f
Compatible with CZ Scorpion. It features a window for round counting.
