RPM Slayer, Revo, T-Maxx 2.5R, T-Maxx 3.3 & E-Maxx 16.8 axle carriers are sold with 1 left and 1 right axle carrier, 2 outer 15mm bearings, 2 inner 21mm bearings, 4 aluminum setscrews, 4 Delrin bushing caps, and detailed instructions to help install them on your truck. Replacement bearing sets (#80570) come with 2 inner 21mm bearings & 2 outer 15mm bearings.