Oh I know there are different kinds of slings, but I think in terms of what my character perceives. And, if I were James, I wouldn't notice the sling type as I was bending to check specks of blood. I'd be looking for a trail, or looking around for the source of the blood, maybe checking to see if Jin was moving up with me, and gauging how worried he was at the sight of blood where there normally wouldn't be any.