Also known as Common Sense outside Europe, again another fastener that was first invented to hold curtains back on horse driving carriages, but once the first group of automobiles came along the turnbutton was used in open air cars to secure curtains. Turnbuttons are probably the most common fasteners used on boat canopies as they can not be opened by accident. They require force to twist the button on the stud which allows the release of the socket. The prongs on the socket come in two lengths to accommodate different thickness of material. There are many types of studs also, again to entertain the thickness of material or the material they are being fixed too.
Made from heavy gauge brass, Nickel plated, Steel srping used in body, Simple twist to lock action, Fastener is locked by twisting the knob, different heights available.
The base has two common heights. The measurement is taken from the distance between the base and the twist knob. Here is why they are often called 6mm base (standard height) and 8mm base (double height)