Cordless angle grinders rotate grinding wheels to remove surface material or rotate cut-off wheels to cut through material. Their head is set at a right angle to the tool body, making them more compact than vertical grinders and allowing for better visibility of the wheel and the work surface. Grinders with side handles allow a two-handed grip to improve stability and control. Angle grinders are commonly used to grind welds, prepare metal and concrete surfaces, bevel cutting tools and material edges, cut metal plates and pipe, and polish concrete, stone, and metal. These tools run on batteries, so they are more portable than corded tools and allow use where access to a wired power source is unavailable. They use brand-specific batteries, which fit different tools from the same manufacturer. Battery voltage and series must be compatible with the tool.