What's cool? Well, its the best made leather sling you can buy, and Les will want to talk to you over the phone before you buy it. It has the heaviest leather, and the heaviest hardware (within the rules) you can find. If you ever have a problem Les will make it right. The biothanes like the Turner are slow to rig for sure, but are stout once set. I prefer to have a little tradition on my rifle, so I have a brown leather sling, rather than rubber or a black sling. That's just me.
As far as the "Navy" sling is concerned, that looks like an M1 style web sling, but it is nylon. You DON'T want a nylon sling. The $4 cloth web sling is head and shoulders above the nylon because the nylon slips!