Silicone and gel absorb shock and soothe tired feet, while carbon fiber provides thermal relief during cold weather.

Focusing on healthful and functional benefits, suppliers of insoles in China are adopting alternative materials on removable models. Fabric is still the most widely used insole material, but an increasing number of companies are now employing silicone, gel and even carbon fiber in releases. These are marketed for alleviation of foot strain. Medical-grade silicone is also said to resist bacterial growth, and be hypoallergenic and odorless. Companies are offering full- or three-quarter-length models, which can be trimmed to fit the shoe perfectly.

Silicone insoles typically have a thicker and harder heel area to reduce pressure and provide additional shock absorption. These are shaped with a slight arch contour and some full-length models incorporate a raised metatarsal pad for extra support. Companies are also offering versions that have gel-filled pockets on areas that need additional shock absorption. Further, some silicone insoles have raised dots on stress-prone areas such as the heel or ball of the foot. These provide a massaging effect to reduce strain and improve blood circulation. In addition, suppliers are releasing gel-filled fabric-covered insoles.

The gel moves with each step of the foot to provide a gentle, massaging effect. Washable, anti-bacterial fabric is used to cover the gel insole. A few companies are offering models with a battery-operated carbon-fiber heating device that can keep feet warm during cold weather.

The insole is made from anti-bacterial and deodorizing materials and the batteries can run for more than 10 hours. Apart from warming feet, the carbon-fiber insole is said to help improve blood circulation.