Base-in Lifesaver vision therapy cards are used to on patients who need to increase their ability to diverge without effort. Developed by Dr Hendrickson, O.D. These Lifesaver Cards are designed for exophores, minus projectors and cases not accepting plus spheres for near and needing base-out vision therapy. These simple cards have been successfully used by many optometrists for over 35 years. Comes with instructions which allow the patients to develop plus acceptance, peripheral awareness and SILO, as well as to integrate balance and total body movement together with speech, audition and rhythm or timing. White Paper or Clear acetate, 6 1/2" x 4 1/2". Includes instructions for patient use. Acetate comes with cloudy protective film to be removed by user.