Measures mutual transconductance which is the best type of tube quality test. Has good-?-bad scale or will measure transconductance directly in micromhos Will test for gas, and shorts between all elements Built in roll chart with settings for all common tubes. Includes obsolete tube and foreign tube roll chart supplement Has 7 & 9 pin minature, octal, 9 &12 pin compactron and nuvistor sockets This item powers up and responds to manual controls. However, it is being sold as is with no warranty. No manual or peripherals are included.