This is an excellent US Divers Matrix Dive Computer.It works great. The batteries are user replaceable. These batteries are about a year old. This is a very easy to use computer. (I own two more that my wife and I use).The manual is available at: /technical_library/matrixmanual_electronic.pdf This was used by my daughter. She lost interest in diving so I don't need it any longer. The only reason I am selling it is because my daughter does not dive anymore. I am selling several additional items, mens BC, womens BC, regulators, one more computers, light, etc. Please check my other sales if you need any great dive gear.I charge only the cost for shipping and will combine items to save you money.