These are the standard 1" (25.4) 5/32" x 16 ball bearing retainers for 1" headsets (sold in sets of two). We also have loose 5/32" bearings. When using loose balls, you need to add enough balls to surround the races and then remove one so they have room to move. Generally speaking this is usually around 25 individual balls. We sell loose balls in bags of 60, just in case you drop one...or two!