RedMax OEM string trimmer commercial 4" tap head pt104 plus part 511010601 includes line fits: Bc250s (standard), bcz2401s (standard), bcz2601 (standard),bcz2610 (standard), bcz3001s (standard), bcz3001sw (standard),bc3401dl (optional), bc4401dw (optional), exz2401s-ph (standard).