5/8" double length lift the dot stud. 10/32 mounting threads. Nickel plated, The double was only used when you had 2 layers of material with the female dot fasteners installed on them attaching to a common male stud.

Studs are normally mounted on windshield stanchions to hold the side curtains on. The measurement given is overall length less the threads.

1926-27 used these to attach the side curtains to the windshield stanchions. You only need 2 doubles per car, 22 singles for a Roadster, 26 singles for a Touring. U.S.A.