The 678 Open is a high-precision, ultra-thin miniature ball bearing engineered for technical applications where minimizing rotational friction is the top priority. Featuring an 8mm bore and a compact 12mm outer diameter, this "Open" configuration lacks physical seals or shields, allowing the rolling elements to rotate with nearly zero starting torque. It is the ideal choice for high-speed systems operating within enclosed, debris-free environments—such as oil-mist lubricated housings or hermetically sealed instruments—where maximum mechanical efficiency and rapid heat dissipation are required.