Built in 12", 16" and 20" sizes, the Sebastian Gold Seal Semi-automatic Production Lathe was supplied complete with length and diameter "gauges" that fitted the bed and cross slide respectively. This method of converting a standard "engine"  lathe into one more suitable for short production runs was, at the time, very common.

Production lathe shown with twin toolpost and Cross-feed and Length-stops fitted . The clamp on the bed (to the right of the carriage)  engaged with a notched bar held in the end of the saddle casting, while the cross slide screw assembly was with adjustable cross-feed notched collars (gauges) and pivoting indexing arms, or "dogs". In use, the cross feed-screw could be turned until the "dog" fell into the notched ring - and the method worked equally well when advancing either the front or rear toolpost into the work.