1. Product Overview The 6309‑2RS1/C3 single row deep groove ball bearing is fitted with double-sided 2RS1 contact NBR rubber seals and C3 increased radial clearance. The expanded internal clearance offsets thermal expansion under long-term high-speed and high-temperature running to eliminate bearing seizure risk. Double contact rubber seals effectively isolate dust, water mist and contaminants while locking internal grease, widely applied to high-temperature heavy-duty