These snap fasteners are to be used for "cloth-to-surface" attachment. The "stud" has a 5/8-inch long "self tapping" screw with a phillips head. Can be used to secure fabric to fiberglass or to wood surfaces. This item includes all three parts shown in the photograph. Sold Each.
Stainless snap fasteners are much "tougher" than the normal plated brass ones. They are more resistant to damage from impact with the dock or another boat than their softer brotheren. They do not necessarily provide better holding power.
Snap fasteners are excellent for securing covers, cushions, tops, etc. These are made from 100% stainless steel. They are highly resistant to corrosion and top quality.
An installation tool is required to flair the button rivet that secures the socket.