One of the many benefits of your Bell Helmet is that it came equipped with a removable/washable interior.  Bell Helmets has manufactured their helmets in 3 various shell sizes (D, E, and F).  You can size any of the above listed helmets accordingly with respect to shell size. 

(i.e. If your helmet is a Moto 6, size 7 1/4, you can put any size replacement liner sized 6 3/4 to 7 3/8 in your existing E-Shell.  However, you CANNOT put a 7 1/2 liner (fits F Shell only) in your 7 1/4, E Shell Moto 6 helmet). 

This chart will help you determine what size replacement comfort foam will fit in your existing Bell Helmet.