Elenco RS400 Resistance Substitution Box, Color May Vary Test possible outcomes in your electronics project Values selected are 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 No soldering or assembly required Add this kit to your STEM curriculum From the company that brings you Snap Circuits - 9 volt battery reqired but not included