ASICS GEL-ESTORIL COURT Tennis Shoes Visible Forefoot GEL - The ASICS GEL system is based on a special kind of silicon that enables optimal shock absorption. GEL units are strategically placed in the midsole and designed to enable specific functions and positions. Board Lasting - Shaped for stability and durability. Silicone Based Material - This is placed in critical areas of the sole. Compression Moulded EVA Midsole - For cushioning under the foot. AHAR Rubber - A tough material placed in critical areas of heavy contact on the shoe for exceptional durability.