Hilly Twin Skin Socklet The Hilly Twin Skin Socklet is the ultimate anti-blister double-layer sock. The Hilly Twin Skin Socklet has fantastic moisture management capabilities and anti-blister properties. It features an anatomical design with abrasion resistance in areas of increased wear and additional ventilation in key areas for improved breathability. The double sock construction absorbs friction, whilst the Meryl Skinlife inner sock wicks moisture to the outer cotton sock, keeping the skin dry and you, more comfortable. It also features soft-touch reinforced heel and toe areas and an arch grip heel for an improved fit. The VentFlex panelling on the front of the ankle also helps to improve performance by helping keep your feet cool and comfortable in key areas. Size Guide Small: UK 3-5.5 / EU 35.5-39 / US Men 4-6.5 / US Women 5-7.5. Medium: UK 6-8.5 / EU 39.5-42.5 / US Men 7-9.5 / US Women 8-10.5. Large: UK 9-11.5 / EU 43-46 / US Men 10-12.5. Extra Large: UK 12-13 / EU 47-48.5 / US Men 13-14.