Check the listing for details. 0-9999.9 Ohm Adjustable Variable Resistance Box Decade Resistor Experimental T. Condition: New, Made in China. Listed at 39.93 USD. The 23022 teaching resistor box adopts a rubber sealed structure. The resistance value transformation method is in the form of a knob switch, which relies on the electric brush rotating to different positions to achieve the purpose of resistance value transformation. Panel layout, wiring principle. The resistance components of this instrument are made of highly stable precision alloy manganese copper wire wound non-inductively on the porcelain skeleton. After strict screening, testing, aging, and impregnation treatment, the resistance value is stable and correct. When in use, connect the circuit through two terminals on the panel and adjust the five knobs to get a resistance value of 0 999.92. The resistance reading is obtained by multiplying the readings of the indicated points on each kn.