This "Companion" Chuck Body is intended for those who already have a chuck kit and simply want an additional body at the best possible price so they can keep their most-used jaws mounted and swap bodies instead of jaws. The 102 mm (4") high tensile steel body features integral pinions to drive the scroll ring, providing the benefit of being able to use a ball-end hex key for easier operation and access behind large diameter workpieces. It also offers the option of adding aftermarket hex keys with longer shafts if you have particularly large work to mount. A backing plate keeps the pinions in place and features indexing holes as well as keeping all the internal mechanisms much better protected from dust and resin, so the requirement for maintenance and cleaning is much reduced. This model is manufactured as an ‘insert' chuck, providing the opportunity to use the chuck on more than one lathe with different thread spindles by simply changing the low-cost insert rather than requiring an additional body. An insert also provides future-proofing so that any machine upgrades will not require a new chuck even if the spindle thread changes, just a change of insert. Inserts are available separately, and you will need to purchase the insert that matches the thread of your lathe spindle.