HiKOKI 878885 O-Ring S-18 for a wide range of compatible HiKOKI and Hitachi power tools including rotary hammers, drills and pneumatic nailers. This replacement sealing O-ring is designed to provide a secure seal within the relevant tool assembly and is suitable for replacing a worn, split, damaged or deteriorated original. Manufactured to the correct specifications for precise fit and reliable sealing performance.