The Adafruit Triple Axis Gyro Breakout is based on the STMicro L3GD20 MEMS digital output gyroscope chip. We include a 3.3v regulator on board for compatibility with 5v controllers like the Arduino. And there are 4 holes so that it can be rigidly mounted.
The triple-axis gyro sensor is a MEMS (Micro Electrical Mechanical System) device consisting of 3 micro-machined ‘tuning fork’ structures on a silicon wafer. These structures are designed to vibrate when stimulated by an electrical signal. When rotated about the axis of the tuning fork, the tines will deflect due to the Coriolis force. This deflection is proportional to the speed of rotation.
The 3 MEMS structures are arranged orthogonally, on the X, Y and Z axis. Deflection on each tuning fork is detected as a change in capacitance between sensing plates built into the MEMS structure and converted to a degrees-per-second rotation rate for each of the three axis.