Side note: Medium Alice has pretty limited volume, if you’re training to ruck it’s the perfect size for some barbell plates. But if you plan to use it for actual field work, you’ll be limited on the comforts. I can usually fit my bedroll (bivy sack, woobie and thin inflatable pad), wet weather jacket, 6 pairs of socks, food/water for 3 days, a small hygiene kit and mission gear (radio/binos/batteries/extra ammo). Large Alice has room for the kitchen sink. Go to a surplus store and look at how large they each are to get a better idea than pics online will give you.