The lining corresponds to the circumference of the rider's head.  KEP lining is available in 12 sizes, depending on the size of the shell: Medium shell: lining from 51 to 58; Large shell: lining from 59 to 62.

KEP Italia's inner lining is a single piece of material and is easy to remove and reposition inside the helmet. It can be washed by hand in cold water or in the washing machine at 30°C. The lining is made from Coolmax®, a fabric made using a fibre able to maintain cool temperatures and facilitate skin hydration, at the same time as allowing any moisture to be rapidly absorbed.

The fact that the lining corresponds to the rider's head size means that riders who alternate between wearing their hair loose or tied up can use two interchangeable linings of different sizes. This feature is also useful for children, whose head size is still growing. Parents can easily buy the next size up and replace a lining that has become too tight, without having to look for a new helmet.