This device is mainly used to check windings insulation resistance in motors of hermetically sealed refrigeration systems, but it can be used in other motors and electrical equipment as well. The scale is from 20 to 1000 megohm. It works with 2 x 1.5 V batteries (type C). Made in the US, it comes with carrying case and instructions. Very good and reliable meter for professional use, a must for HVAC technicians. You can visit the manufacturer's web site for full description, specifications and applications. https://www.supco.com/web/supco_live/products/M500.html