What’s the difference between the Z-Trek and Z-Trail sandals?

The main difference between the Z-Trek and Z-Trail is the sole. The Z-Trek has a 5.5 mm solid rubber sole that is extremely flexible and allows the most ground-feel. The Z-Trail sole has a 10 mm sole made up of 3 materials: rubber and Trail Foam for the outsole, and a soft layer of Barefoam for the top sole. While still light and flexible, the Z-Trail sole does not offer as much ground-feel.