Mine came with batteries installed and 3 extra batteries for later. Well, "later" happens to be after one use. I got one additional use with the second set of batteries. Now I'm left wondering if I want to buy more batteries, or spend the money on a different level.I don't have enough experience with cell batteries to know how long they are supposed to last. Would Duracell give me considerably longer, or does the laser require more power than cell batteries are designed to provide? (IF you have the answer to this, please leave a comment to let me know).Anyway, on to how well it otherwise functions. First, there were no directions included to figure out how to really adjust this thing. There was a few lines on the box, but not even close to enough information to help me.The positioning of the on/off switch is terrible. Too easy to bump it on or off. Carried it to work in my bag and had to keep reaching in to turn it off because the switch kept getting hit. Unnerving since maybe I would have been able to get at least one more use out of those batteries.It did function for what I needed. I needed to put up two separate bulletin boards in my class spaced a good six feet apart. This allowed me to get them both level and placed at the same height. Only problem was I needed an additional human so that one could hold the level while the other marked the spot 6 feet away. If this could temporarily attach to the wall it would be much more useful.