Shure BG-4.0 in great condition. 

The BG4.0 microphone utilizes an advanced condenser transducer design for use in professional instrument sound reinforcement and project studio recording. Its electret cartridge has a wide frequency response for natural sound reproduction, and its high sensitivity and low noise make it an ideal choice for producing quality demo tapes. The BG4.0 also maintains a cardioid polar pattern throughout its frequency range which ensures high gain-before-feedback and maximum isolation from undesired sound sources. Operating voltage is supplied by phantom power from a mixer, or an internal AA battery for 10,000 hours of continuous use. Typical applications for the BG4.0 include acoustic guitar, drums, stringed instruments, and vocals (when mounted on a stand).

There is no difference between the BG 4.0 and the BG 4.1; the model number was changed to reflect new packaging