This encoder pair is nicely built overall, I got it working with DF Rover right away. How to incorporate encoder data into your code is another story. Depending on your goals you may need some (a lot) of experimenting with the code. So, first of all, I'd suggest to buy and attach a Bluetooth Bee to the rover to monitor encoder data (and other parameters) wirelessly via a serial port. Secondly, after some of that experimenting and/or re-assembling the rover a few times you may realize that one of the encoder PCBs got loose. After one such accident I decided to glue the encoder PCBs (not the wheels) with 5 min epoxy instead of hot glue. Whatever works ;)