Here is the solution to finding the optical center on today’s smaller frames. The Frame Riser Plate lifts the frame to the geometric center. This eliminates the false reading of vertical prism caused by checking above the optical center. The plate easily attaches to Marco and B&L Lensometers to extend the lift needed for today’s smaller frames. Offered in 2 styles – Small plate with Marco clip. Slightly larger plate with the B & L clip.