The Automatic Feed Spool (AFS™)) is the technologically advanced line feed system found on Black & Decker string trimmer products such as the Grass Hog™) Trimmer/Edger, and the 12" Cordless Trimmer/Edger. Using centrifugal force, the system monitors the amount of line being used and feeds more line automatically as the cutting line shortens.
The AFS system provides three main benefits.
You do not need to bump the trimmer on the ground or push a button to feed the line in the trimmer
Because the line automatically feeds as needed, you can now enjoy non-stop trimming and edging
With no bumping and less starting and stopping, there is less wear and tear on the trimmer