This new shaft stores inside the declination axis of the Mach1GTO for the ultimate in portability and allows you to use the same 10 lb. (10SCWT) and 18 lb. (18SCWT) counterweights that you may already own for your 900 or 1200 mounts. We are also now offering a 5 lb. counterweight (5SCWT) with the larger 1.875" center hole to accomodate lighter loads. The overall length of the shaft is 10.70" and its useable length (excludes the part of the shaft that threads into the mount) is 9.625 ". It requires the same new machined safety stop knob (M12676) that we now use with the Mach1GTO''''s'' bigger siblings. It will also accept the 9" shaft extension (M12675). All counterweights and and shaft options are sold separately. This new counterweight shaft can also be used with Mach1GTOs that are already in the field.