Enduro Bearings - Enduro ABEC5 bearing 6803 Stainless Steel LLB 17x30x7mm 17.1g

Enduro ABEC5 bearing 6902 LLB 15x28x7mm 15.7g

Balls:
440C Stainless Steel Balls are within 5/1,000,000″ round. These are military level specification, used for precision equipment. R-64 hardness, of the highest grade.
Also Races are made of 440c stainless steel, polished to a mirror finish for ABEC-5 precision and noiseless movement. Nylon with graphite retainers are virtually frictionless while providing constant lubrication

Races:
440C Stainless Steel Races
Vacuum de-gassed process for the purest chromium alloy steel, hardened to R-62, extremely tough and very durable. Polished to a mirror finish for ABEC-5 precision and noiseless movement.

Retainers:
Graphite/Nylon Ball Retainers
Nylon with graphite retainers are virtually frictionless while providing constant lubrication.

The ABEC-5 Standard:
To meet the ABEC-5 standard, bearing design must pass all tests, which include noise testing at high RPM, extremely close tolerances for I.D. and O.D., roundness of ball, trueness of the races and micro surface finishes of balls and races.

Seals:
Two NBR 70 rubber  LLB Dual-Lip seals with low contact type seal, which rides in a matching groove machined into the bearing.