This set of 500 bike ball bearings helped me fix my 6 year old daughter's bike. My daughter's 12" bike had a ruined front hub from scratched bearings and dried grease. So I opened up the hub, cleaned with brake cleaner, re-greased the inside and installed ten 3/16" (4.7mm) ball bearings. After that, my daughter was amazed at how smooth her bike got and how quiet it got. It was. At $19.99 (as of May 18, 2021) I think the price is great, as is the quality.