The Machinist TP Tool Lathe Mill Starrett No 657 Magnetic Indicator Gauge Base Holder is a precision engineering tool designed to hold and align magnetic indicator gauges on lathes and milling machines. Made by the reputable brand Starrett, this base holder ensures accurate and reliable measurements for machinists working in the manufacturing industry. Its magnetic feature allows for easy attachment and positioning of indicator gauges, making it a must-have tool for precision machining operations.