This is the Associated replacement parts set for the RC10T3 truck. This package includes twelve ball cups on a plastic parts tree. These are made of a black nylon and are for 4-40 threaded rods.
Note: These are the cups that screw into a rod (like a tie rod or an upper suspension linkage rod) and "cup" over the linkage ball. This can be used as an upgrade for any 4-40 ball cups. They appear to be made out of a stronger material than the "stock" Associated cups.