This is a Boca 14x25.4x6mm Ceramic Radial Bearing. This bearing is intended for use in a Nitro Engine with compatible dimensions. This bearing is open to allow oil to lubricate it during use.
Ceramic balls weigh up to 40% less than steel balls, depending on size. This reduces centrifugal loading and skidding, so hybrid ceramic bearings can operate up to 50% faster than conventional bearings. This means that the outer race groove exerts less force inward against the ball as the bearing spins. This reduction in force reduces the friction and rolling resistance. The lighter ball allows the bearing to spin faster, and uses less energy to maintain its speed.