The KSO, which stands for ‘Keeps Stuff Out”, is Vibram Five Fingers most popular barefoot shoe due to its near limitless versitility. The Vibram KSO is great for high performance trail running and OCR’s, but is also great for running and walking on smooth roads or on semi-technical terrains and grass. The shoe is also perfect for backwoods trail hiking in dry or in wet, humid conditions and can be used for Cross-Fit, lifting, kickboxing and karate, high intensity training, rock climbing (works just as well as any climbing shoe), golfing, soccer, white-water rafting, swimming and for everyday casual use!