QA1's AIB & AIB-T Series spherical bearings are made from chromoly steel to offer better wear characteristics than their traditional carbon steel counterparts. These spherical bearings are available with an optional self-lubricating PTFE liner. BALL, 52100 Bearing Steel, Heat Treated, Hard Chrome Plated, Precision Ground, , LINER (AIB-T), PTFE, Self-Lubricating, , RACE, Chromoly Steel, Heat Treated, I.D. Protective Coated for Corrosion Resistance, Oil Coated, Mfr.'s Option - Heat Treated Stainless Steel.