30 Pack convenient, pocket-sized, color code guides for determining standard and precision resistor values. Each card measures 6" x 3" and the reverse side includes many useful formulas, conversion factors, and a list of commonly used resistor values. These guides are perfect for distributing to students in a classroom or laboratory. Reverse Side: Ohm's Law Formula for DC Circuits, Resistors in Series, Resistors in Parallel - General Formula, Conversion Factors such as meters to inches to feet, kilometers to miles, inches to centimeters, etc