I just purchased a BlackRapid R-Strap for my 40D (review will be forthcoming). When searching for a place to purchase the R-Strap, I found that most places online were sold out of the RS-4 which I stupidly assumed was the latest, greatest and best version of the R-Strap. It wasn’t until I looked at ePhotoCraft’s description of the R-Strap that I actually learned the differences between the different models of R-Straps:

“The difference between the RS-1, RS-2, RS-3, RS-4 straps:

* RS-1: Black fabric, slim design, no storage pockets.
* RS-2: Black fabric, Front flap opens and has a zippered pocket on the inside for storing small things like memory cards. Front external pocket is good for smaller cell phones (not compatible with Iphones or PDAs).
* RS-3: Camouflage Ripstop fabric, Front external pocket is good for smaller cell phones (not compatible with Iphones or PDAs). Does not have flap that opens like the RS2.
* RS-4: Black fabric, front zippered pocket for storing small things like memory cards or business cards

Sizing:

The R-Strap is very adjustable. RS-1 & RS-4: 60″ (30″ from top of left shoulder to right hip). The max circumference of the RS-2 & RS-3: 72″ (36″ across torso top of left should to right hip bone.”

I ended up getting the no-frills RS-1.