Equation Unisex Quartz Water Resistant Analog Black Strap Watch Solve the math to read the time on clever math equation analog watch that features mathematical equations for each hour Unisex watch perfect for math, science, tech, geek, engineer, teacher appreciation, Fathers Day, birthday gift Black silicon gel band strap goes with everything; watch face 1 5/8 inches diameter Water resistant watch for men and women with replaceable button cell battery, wind up stem Red sweep 2nd hand with white hour and minute hands; 1 year warranty