The A axis rotates ± 93 ° in the X-Y plane. The B axis rotates in the Z plane within ± 300 °. You can use the control wheel to lock the head joint in any position. Each time the head is repositioned, the stylus needs to be recalibrated. TP20 modules can be replaced without the need for recalibration, as long as the position of the head has not changed.