Perfect for someone who wants to take their sensory stimulation to the next level, the Duo is a double-sided insole, featuring our highest-level stimulation on one side and our Activation-level on the other. When you start to become accustomed to one level of stimulation, simply flip the Duo over. Recommended for: Maximum level of foot activation and stimulation  Those who wear Naboso Insoles everyday as it offers texture variability  Avid minimal shoe wearer who is looking to up their barefoot stimulation  Thin enough to work with all types of footwear.    Replace the existing insole or use it on top of an orthotic.   Designed to be with no socks or with thin socks. Non-Toxic | Latex-Free | 100% RecyclableBacked by 30 day satisfaction guarantee