If you find yourself carrying around several pairs of glasses because you need different strengths for reading using a computer or shopping these Glasses are the ideal solution. Simply turn the dials to change the lens power from +0.00 up to +2.75. Each lens is comprised of two wave-shaped polycarbonate plates that are able to glide across one another to alter the strength. Each lens can be adjusted to suit your vision when you think it is necessary all at the turn of a dial. Comfortable & easy to use they come in a hard case. 16+.