Product Description Size: 3/4/6 packYou are free to choose. BLACK+DECKER Auto Feed System (AFS) thread trimmer replacement spool eases the tedious work of hand-feed spools. The 30 foot replacement spool for automatic winding has been designed for use with Black & Decker auto-feed trimmers and features a .065" diameter line. It uses centrifugal force to automatically feed the cutting strand while avoiding bumps and problems. Compatible with: CST1000, CST1200, CST2000, GH400, GH500, GH600, GH610, GH900 and more. 1.This spool is the perfect replacement for the BLACK + DECKER replacement spool system 2.Compatible with most BLACK + DECKER string trimmers; The 30ft spare line is factory spooled for superior feed 3.This spool uses centrifugal force to feed the trimmer line as needed. Same function as BLACK+DECKER original coil, you don't have to worry 4. Optimized for extremely high power and load.