Simply put the Luna Sandals Osos are the absolute best piece of footwear that I've used to date. Their versatility, grit, and all around toughness have taken me very far. I love them and when I'm out there suffering on the trails you'll most likely see a pair of these guys on my feet. I wore them on my very first 50k in October of 2015 and everyone was impressed with my age at 16 and that I was running in sandals. Even with Born to Run and the minimalist craze that happened a few years ago, true minimalism like running in sandals or barefoot is still very surprising and impressive to most. But, I am simply trying to get back down to basics. At the minimum: a pair of sandals, shorts, and a bottle and I'm at my happiest. And these sandals bring me down to that simplicity.
The name Oso translates to Bear in English and the tread on the sole of these things is as tough as a bear. Just like bears, anywhere in the mountains you want to go this tread will take you. I have never had a problem with the tread, except for the fact that due to its very rough nature mud tends to be more prone to staying stuck than on something like the Leadvilles. I love the tread and the Vibram sole seems to be of a high density making rocks almost not a problem, but don't expect it to be a cushion-y float on clouds. The dense tread makes it tough, but stiff, so you just have to get used to it.
Like most other Luna Sandals the Osos have the MGT (Monkey Grip Technology) on their footbed. Locking your foot in and keeping it stable for the whole run is what the MGT does and does perfectly.
Again like many other Luna's these use the Performance Laces. And again they are amazing, being the second part to the locking in your foot process. Apart from some fraying that is bound to happen and eventually needs replacement, these laces are great.
Coming in at a mere 7 oz (Men's Single Sandal Size 9) the Osos are light, durable, tough, and just gnarly! I love them and I hope you do to.