Greg, as pictured here, the hole is a QD (Quick Detach) mounting hole : https://ar15discounts.com/products/b5-systems-bravo-mil-spec-stock-black/ --------------- You would just need an MLOK attachable QD attach to place where ever you like on the MLOK hand guard to attach your sling : budsgunshop.com/product_info.php/products_id/718006031/m-lok+quick+detachable+sling+mount+black

Yes, if you look at the stock you can see a little hole. That's meant for a qd/quick detach swivel Wich can be used for a sling. So if you purchase a qd swivel you can mount a one point sling. Or you can purchase a mlok swivel Wich will attach to the handguard so you can use a two point sling. Just depends what kind of sling you want to choose. Hope this helps.