We race two times a month me and my son run a class. So i replace those bearings twice a month and that 8 bearing a month. At $12 for 10 pack thats $1.20 each so about $9.60 for a month. I have never had a clutch bearing go out after doing it this way. If i went cermics it would cost $10 for 2 bearings. So money is the main thing. Also Answer-RC bearings are great.