All soles are thin, flexible and zero drop. The difference is grip, durability and whether you can ground.
Leather solePure vegetable-tanned leather outsole: the most ground feel. Best indoors and on dry days.
Leather sole + copper rivetThe leather sole with a pure copper rivet through it, so the shoe can ground you on soil, grass or stone.
Leather sole + 2 mm rubberA thin 2 mm rubber layer under the leather sole for grip and wet days. Still thin and flexible.
Leather sole + 2 mm rubber + copper rivetRubber layer for grip plus the copper rivet for grounding.
EVA soleA light, cushion-free EVA outsole: flexible, grippy and very light.
EVA sole + copper rivetThe EVA sole with a copper rivet for grounding.
Black rubber soleA 3 mm flexible rubber outsole in black.
Tan rubber soleThe same 3 mm rubber outsole in tan.
Black soleThe 6 mm flexible rubber outsole in black.
Tan soleThe 6 mm rubber outsole in tan.
Off-white soleThe 6 mm rubber outsole in off-white.