I needed more counterbalancing capability. I always have to travel and hike to my dark sky locations, so I wanted the lightest option. I could have purchased a second counterweight, but the extension shaft provides additional balancing leverage for less additional weight to carry. Not all the pictures show the same thing: what I received was a shaft with male threads on one end and female threads on the other identical to the original shaft that came with my SkyGuider Pro. (An additional retainer screw to keep the weight from slipping off the shaft was not included, though it is shown in some photos.)

The shaft arrived promptly and in good condition. Unfortunately there is no screw included, so the picture is somewhat deceptive.

The Sky Guider Pro is excellent in every respect; the design & manufacture are flawless. The same holds true for all of the additional parts that are provided with it, with the exception of the base that the mount is attached upon. The adjustments for DEC or altitude are easy to manage & accurate using the scale on the mount. RA or azimuth adjustments are not so easily made having to manipulate two rotating knob & no scale up which which to base the amount of movement. And I installed an iPolar polaris alignment system in the mount & was super impressed with the responsiveness & customer oriented attitude of everyone in their support group. This is a very solid performer with great support from its manufacturer.