This Decade Resistance Box provides variable resistance over six orders of magnitude. The resistance is chosen using knobs on the box. The maximum resistance is 1,111,110 ohms, and maximum recommended working voltage at that resistance is 500V AC for 30 seconds. The Decade Resistances have been designed for general purpose lab applications. Do not use for high voltage applications. Product measures 7.75" wide, 4.75" long and 1" tall.