Product Description Individual hand-held prism flippers. The orientation of these flippers is in base-in and base-out. Lens Types are: 1 Diopter (1^+1^) = 2^ total 2 Diopter (2^+2^) = 4^ total 3 Diopter (3^+3^) = 6^ total 4 Diopter (4^+4^) = 8^ total 6 Diopter (6^+6^) = 12^ total 8 Diopter (8^+8^) = 16^ total Note: All products sold on Accuspire.com should be used by qualified clinician and should be purchased by or on order of a qualified clinician.