This part allows you to fix the thumbstick on your original N64 controllers that are very prone to wearing out and breaking. Great part! In lightly used condition. There is a small amount of free play in the thumbstick, but they will allow you to control your gameplay well.
The only tool you need is a small screwdriver.
Thumbsticks are priced and graded according to degree of movement in thumbstick. From least movement to most movement: Best, Better, Good, Fair.
The ones with a missing prong have one of the three tabs on the back that are broken off. These help in locating the thumbstick in the correct spot during the repair, but once you screw it in tightly, they aren't needed, and will work perfectly well -- at a great discount!
Free Nintendo 64 Controller Repair Guide!