Foldable, Flexible Silicone Rubber Solar Calculator Rubber Calculator Are rubber calculators for bending the books? Adding up bounced checks? Bite your tongue. Or bite this calculator. It won't hurt, because it's made of foldable, flexible silicon rubber. Solar powered, too. Measures 4-5/8" x 2-7/8" with a 2-7/16 x 1- 5/16" solid section at the top for the 8-digit display. We'll pick one for you in yellow, orange, purple, green, blue, magenta or something equally attractive.