With a 3mm thick Aerospring foam and flexible heel cradle, the Superfeet FLEXthin insoles offer long-lasting comfort for most footwear. The Superfeet series offer excellent introduction to the Superfeet experience. Durable Construction: keep their shape for reliable support and comfort for up to 12 months or 500 miles Aerospring Comfort Foam: 3mm thickness, durable, viscoelastic closed-cell foam layer that absorbs impact for comfort Moisturewick: with long lasting odor control Dynamic Shape: contoured to stabilize and support the foot, reducing stress on feet, ankles and knees Flexible Heel Cradle: provides structure and stability Ventilated Forefoot: improves air circulation and breathability Beveled Edge: improves the fit in tighter fitting footwear Item# FLEXTHIN