Product description Size:3/4/6 packYou are free to choose. The BLACK+DECKER string trimmer Auto Feed System (AFS) Replacement Spool eases the tedious work of hand winding spools. Designed for use with Black & Decker auto feed string trimmers, the 30 foot factory wound replacement spool features a .065 inch diameter line utilizes centrifugal force to automatically feed the cutting string while eliminating bumps and hitches. Compatible with: CST1000, CST1200, CST2000, GH400, GH500, GH600, GH610, GH900 and more. 1.This coil is the perfect substitute BLACK+DECKER replacement spool system eliminates time spent hand winding string trimmers 2.Compatible with most BLACK+DECKER string trimmers; 30 feet replacement line is factory wound for a superior feed 3.This spool utilizes centrifugal force to feed the trimmer line as it is neededSame function as the original spool of BLACK+DECKER, you do nt have to worry about any problems 4.Optimized for extremely high performance and load.