Selling the last of my mics...
The Apex 191 is a small-diaphragm electret pencil condenser with cardioid polar pattern.
It is essentially the same mic as the Apex 190, but includes an internal battery compartment (for a single 1.5V AA/UM3 battery), enabling the 191 to be used where phantom power is not available.
Read more:
http://recordinghacks.com/microphones/Apex-Electronics/191