The Kata 3n1-10 is the bag I'm currently testing. It comes in three sizes and mine is the smallest, but it's a good day bag. One of the biggest problems I have with slings is that the straps are usually fixed to the bag, meaning you can only wear them on one shoulder (typically the right). So if that shoulder gets sore from carrying the load, you're stuck. The 3n1-10 solves this by giving you two straps--one on each side--that can either be used one at a time, or as a back pack with the straps crossing your chest or just straight down.Read more about the Kata 3n1-10.