Most drills have two speeds, but some drills have three or beautiful adjustments. The fearing offers versatility depends on the task you will perform. Set 1 is low speed & high torque used for driving screws. Set 2 is the medium speed seven torque used for drilling and driving. Set 3 is the top speed for drilling and driving faster. Don’t change the speed switch while the tool is working, and it causes damage to the gears.