fairywill Replacement Heads Soft Firm Bristle for 507 508 917 659 Black Series
Material : ABS/TPE/Dupont nylon. Bristle type: Soft /Firm Option. Electric Toothbrush Head x 4/8/12 with Soft/Firm Bristle Solely Compatible for FW-507,FW-508, FW551,FW2011, FW917,FW959,FW515 Series Toothbrush.