A complete set of Teller Acuity Cards® II consists of sixteen 25.5 x 55.5 cm (10 x 22 inches) cards, each of which has an approximately 4-mm diameter peephole at the center and includes a Blank and gratings from .23 to 26.0 cycles/cm. Fifteen of the cards contain patches of square-wave gratings (vertical black-and-white stripes), approximately 12.5 x 12.5 cm in size, centered on one-half of the card. The gratings have a 50/50 duty cycle (black bar width = white bar width), with a contrast of approximately 60-70%. The left and right edge of each grating is finished with a black or white stripe of 1/2 of the usual width in order to minimize the visibility of the edge of the grating. These 15 cards have the following spatial frequencies (specified in cycles/cm): 0.32, 0.43, 0.64, 0.86, 1.3, 1.6, 2.4, 3.2, 4.8, 6.5, 9.8, 13.0, 19.0, 26.0, and 38.0, with approximately one-half (½) octave difference in spatial frequency between cards. The Teller Visual Acuity Cards Half Set includes 8 cards ranging from .23 to 26.0 cycles/cm New Box Included With New Purchase. Individual Replacement Cards are also available for purchase here. Teller Acuity Cards® is a U.S. registered trademark of the University of Washington and used under license to Precision Vision, Inc.