Elenco  Resistor Substitution Box - RS-400 Test possible outcomes in your electronics project with this PRE-ASSEMBLED Resistor Substitution Box Values selected for your resistance substitution box were determined to be the most commonly used in modern solid-state circuits Values are from 10 to 1,000k (1 meg) in 24 steps All resistors are 5% tolerance 1/2 watt Includes: PCB, electronic components and instructions PCB measures 611mmX1016mmX16mm Add this kit to your STEM curriculum - 9 volt battery required, not included