FN 20100503 502 15rd 22 LR Black Steel
https://www.tandktactical.com/shop/845737013455-fn-20100503-502-15rd-22-lr-black-steel-29350
https://www.tandktactical.com/web/image/product.template/29350/image_1920?unique=eb06a31
This magazine is compatible with your FN 502.
