This is a high quality encoder that can be configured on 16 different resolutions (dip switch setting). The price/performance ratio is very good and it's widely used
The package includes enough accessories to allow easy installation on many different kind of motors, with different size and shaft diameter. The assembly instructions document explains how to.
To connect the encoder to the circuit is highly recommendable to use the specific:
AMT102-V Encoder Wire Harness.
How to use the encoder to measure the speed of the robot using dsPICC33F Input Capture Module.