Unplug the clippers and locate the adjustment lever on the side of the unit. Place the flat top edge of the cutting blade on a flat surface. This makes it easier to understand the different positions of the adjustment lever.
Raise the plastic lever to the vertical position to set the trimmer to the shortest possible setting. Move the lever downward to achieve longer cuts. In its lowest position the blade makes the longest cuts possible.
Remove the pair of Phillips-head screws on top of the trimmer and detach the current blade if your model does not have an adjustment lever. Place a different-grade blade in position and replace the screws without over-tightening to make a different-length cut.