A layer of resistance wire wound on a porcelain tube shpported by pressed metal end cheeks. 
Use as potentiometer or rheostat.
Double contact point, with three 4 mm socket terminals.
20 ohm, 4.5A. 

Science Lab Supplies is a leading Rheostat manufacturers, suppliers and exporters that offers wide range of Rheostat at most competitive prices.

Rheostat

SKU: SL-566