S size. Confident you may need some force, but this is due to the fact that the short adjust buckle is held in place by friction. This may be the weak point to somebody but I have discovered this being of no complications for me, the sling has never skipped https://remingtontgrbj.tribunablog.com/not-known-factual-statements-about-magpul-d-60-drum-magazine-49047537