This is a BK Precision 510 Transistor Tester.  It is in very good condition and has been tested.  See the transistor under a test.  This item tests transistors, SCR’S, and FET’S.  It will test the device and identify if PNP or NPN and identify the leads.  Includes leads and case. Requires 4 AA batteries not included.  The small transistor shown being tested is not included.  Instructions are on the back of the unit.