BK-5044 – 5/32 (0.15625) Grade 25 Steel Balls – 200 pieces Loose ball bike parts are still out there, so Enduro carries the loose balls you need to complete the job. Grade 25 balls meet or exceed 25/1,000,000 tolerance of sphericity and is considered extremely round. Only a few years ago, Grade 25 would be considered a very high grade ball, used only in the best hubs and bottom brackets. Today, Enduro′s entry-level ABEC-3 bearings feature Grade 10 balls and then Grade 5 or Grade 3 as you go up in price and performance.