The PALs System is what you see on the Ballistic Vests we soldiers wear, as well as on most tactical packs, and a few other places. It's basically a ladder of webbing sewn on to our vests at regular intervals which allows us to securely fasten gear to ourselves. The Molle locks are what we use to fasten said gear to our vests. They slide through several of the loops on our vests and interlock with loops on the piece of gear you are attaching. It's a pretty decent system (much better than alice clips), and if you attach a piece of gear (ie a sheath) to your kit using the molle locks, it's not going anywhere and is really stable. For the uses you might have (assuming you don't have a ballistic/tactical vest) the molle locks can be used to attach the sheath to a belt or pack, and should form a pretty secure connection. Anyway, hope that answers your question. Have a good one!
