I'm using this in a very simple and non-critical measurement function, so I'm just guessing at the accuracy. It's also easy to use. Good guide there. A mini screwdriver is included in the scope of delivery. This is used to remove the screw on the opposite side of the battery compartment so you can remove the battery cover. IT HAPPENED: After loosening and/or removing the battery cover, it still doesn't slide off. I DO NOT RECOMMEND PURCHASING THIS PRODUCT.