Replacement/Seperate lining for the SamShield Premium Helmets. Can be used as replacement/change of existing lining or for padding out the helmet, giving a better fit to the shape of the head. If you wish to change the helmet size by using a different liner then you can do so but only within the same shall size. The shell sizes are as follows: Medium Shell: 52, 53, 54, 55, 56 & 57 Large Shell: 58, 59, 60, & 61 X-large shell: 61, 62, 63 & 64