This trial set consists of: plus (+)/minus (-) spherical lenses (one pair of each) ranging from 0.25 to 6 diopters (48 lenses) plus (+)/minus (-) cylindrical lenses (one pair of each) ranging from 0.25 to 2 diopters (16 lenses). The diameter of each lens is a standard 38 mm. Trial lens set has 8 open slits for extra lenses. Lens set can be customized. Please call us at +65 6742 5940 if you have a request for special lenses.