Synthetic CHOOSING ADVICE:Should buy one size smaller. Eg: order size 7 if you wear size 8 normally. Please see the second picture for more details Our Size Label: US Size 5= European 37, US Size 6= European 38, US Size 7= European 39, US Size 8= European 40, US Size 8.5= European 41. size 5: 9.29Inch size 6: 9.53Inch size 7: 9.76Inch size 8: 10Inch size 8.5: 10.24Inch Note: The above are inner length. You can also make a choosing decision after measuring your feet. Waterproof and lightweight,shaft measures approximately 8.85,boot opening measures approximately 12.7,heel height approximately 1.10 No lace design,can match with different of clothes.