I think the spring loaded arm is to protect the indicator if you over travel. The 711 is in excellent working condition and comes with the ball socket arm shown attached plus case and accessories shown.There are 2 more size indicator arms in the small tube. This is a great little tool that sets up very easy. The item "Starrett 657A Magnetic Base & 711 Last Word Dial Test indicator Machinist Tools" is in sale since Thursday, August 20, 2020.
This item is in the category "Business & Industrial\CNC, Metalworking & Manufacturing\Metalworking Inspection & Measurement\Indicators". The seller is "fergy1979" and is located in New Bedford, Massachusetts. This item can be shipped to United States.