Description The unique ingredient in these socks is the Polygiene® technology. Made with low concentrations of silver salt, which has anti-microbial properties and is naturally present in water and soil, to safely eliminate the ability for bacteria and fungi to grow. This is only active on the sock itslef and does not interfere with the skins bacterial flora. The added benefit of Polygiene® odour control will not wash out as the technology is bound and permanently integrated into th sock. The Marathon Fresh is also made with LYCRA® SPORT fibre to ensure a close, comfortable fit. Socks designed and manufactured by HILLY, the UK's premier technical performance sock company for runners – founded by Ron Hill. Polygiene® – permanent odour control Mid-level anatomical cushioning in key pressure zones for optimum comfort Flat under toe seam construction The unique ingredient in these socks is the Polygiene® technology. Made with low concentrations of silver salt, which has anti-microbial properties and is naturally present in water and soil, to safely eliminate the ability for bacteria and fungi to grow. This is only active on the sock itslef and does not interfere with the skins bacterial flora. The added benefit of Polygiene® odour control will not wash out as the technology is bound and permanently integrated into th sock. The Marathon Fresh is also made with LYCRA® SPORT fibre to ensure a close, comfortable fit. Socks designed and manufactured by HILLY, the UK's premier technical performance sock company for runners – founded by Ron Hill. Polygiene® – permanent odour control Mid-level anatomical cushioning in key pressure zones for optimum comfort Flat under toe seam construction