When it comes to the BlackRapid sling straps, I'm much more a fan of the strap than the connectors, but the Sport Slim is probably my favorite strap out of all the ones I've been using from any company. The company makes a series of straps in a couple of widths -- a standard width and a skinnier version for slighter frames, as well as a curved strap that more comfortably fits women's frontal topography. But the Sport has a particularly nice feature: a second strap that wraps around your left (or right, in the case of the LS version) shoulder to provide additional stability.
Though targeted at the active crowd, the strap makes a big difference when you're doing something that requires both hands or if you've got a relatively heavy pro body. Whe Sport Slim has a movable cam buckle on each side of the carabiner (Connectr) that holds the tripod-mount connector (Fastenr), and the buckles act as stops to prevent the camera from sliding too far in either direction. On slings without the underarm brace, those stoppers become moot, since the whole strap generally slides or flops when you lean forward.
The main strap's 63 inches long and the shoulder pad is a little over 3 inches at its widest. You can also buy the underarm strap, dubbed BRAD, for use with other BlackRapid straps. I like the webbing, which while lightweight doesn't seem to wear, or show wear, as much as some. The shoulder section is nicely padded covered by polyester and ballistic nylon. It's appropriately stiff -- not too much, not too little -- and very comfortable. The BRAD works best when you can get a snug fit; on nylon jackets, especially those aren't very fitted, it's hard to get the BRAD tight enough and the strap tends to slide off.