Some model kits are supplied with proprietary servo arms which are
very commonly 25t.
With this gear, it is now possible to use such servo arms with JR PROPO servos (Which are all 23t)

Bearing: upper/10pi, bottom/10pi

Compatible model: S8931+, S8935+, NX8921, NX8925, NXB8921, NXB8925, etc