High-temperature deep groove ball bearings: consist of only rolling elements without a cage; 

can meet working conditions of around 300℃; produced to normal tolerances;

 have a much larger clearance than normal bearings;

 therefore, they are usually not suitable for high-speed applications and are classified as low-speed high-temperature bearings. 

They can typically run for extended periods at speeds of up to 200 revolutions per minute.