Letter "E" Acuity Chart is made on non-reflecting, matte finish cardboard and has a brass eyelet for wall mounting. Also known as a Tumbling E or Illiterate E chart, this classic visual acuity chart measures 10" wide x 28" high. Western's Letter E Acuity Chart is designed to be read at a standard vision testing distance of 20 feet and has a Snellen Rating of 20/200 to 20/15. The blue, green and red bars which are printed on this snellen e-letter eye chart serve as a reference point during acuity testing and also hint as to the patient's color perception. An interesting additional feature of this 10" x 28" Snellen Letter "E" Chart is that it folds in half with a hinge for portability.