This turret drive has a large slewing bearing for structural support and the ability to pass objects through the middle. The drive gearbox and motor (not included) are positioned on the outside and includes the hardware to be mounted going up or down. The drive pulley is an 8mm bore with 16 teeth and the bearing has a 13.25 inch bore with 254 teeth.
As of right now, we aren't planning on restocking the Turret254 for the 2020 season. The new Turret240 is a much better solution that teams should consider as a replacement.