Gas Purge Bulkhead fitting for Lima Model XT-200 Welding Positioner.  For retrofit, a hole will need to be drilled into the case to accommodate this fitting.
 
This part is only required as a service part, or if you are converting an existing unit to gas purge.  If ordering a new unit, check the gas purge option, and your positioner will be equipped with this part and all other required parts pre-assembled and ready to use.