Knee-high boots Princess Polly Lower Impact Upper, lining & insole: 100% water-based PU Outsole: 100% rubber Faux leather material Zip fastening at side Rounded toe Padded footbed Block heel Heel height: 8cm / 3.1in Calf measurement US 8: 40cm / 15.7in , allow 1-2cm variance between sizes Water-based PU is manufactured using an entirely water-based solvent, reducing the need for harsh chemical alternatives. Read more about our Lower Impact Range.