These socks use hydrostop technology which is silicon free elastication for a secure fit that acts as a barrier to prevent wate ingress through the top the stretchdry construction is breathable waterproof and windproof features stretchdry construction waterproof breathable and windproof technology hydrostop silicon free elastication for a secure fit and acts as a barrier that reduces water ingress through the top merino wool lining for moisture control and comfort elasticated ankle