This bike "computer" came with a great instruction manual that is clear and easy to follow. This comes with two batteries, the zip lock cables to attach the parts to the wheel, and the O ring to attach the LED screen to the handle bars. It takes a quarter to unscrew the back of the case to insert the battery and screw it back on tight. The part that attaches to the LED screen is put on the bike with an O ring that holds it solidly there. You can change the time from 24 hour to 12 hour, which is nice, and adjust other features to display what you need to see. It is very well made and functions perfectly. The screen is easy to read. #RankBoosterReview #Sponsored https://www.amazon.com/gp/product/B013SD1X9W #Raniaco