Single speed only but enough power. One catch is that it's not a 1/4" grinder, it's a 6mm. This isn't a huge problem as most burrs and grinders have a 6mm shank, but can be a problem if you use an existing one Have a 1/4" tool as the collet doesn't accept shanks that size. I've used this grinder mostly. for hassle free deburring and spot grinding on weldments. I didn't find the batteries drained as quickly as I thought and use them interchangeably with one corded straight grinder (although the corded grinder has variable speed and is therefore my favorite)