Original replacement silver "acorn head" leg bolts for Data East, Sega & Stern pinball machines.
They are also compatible with Williams & Bally machines.
These bolts have slightly more pronounced acorn head corners than Williams & Bally leg bolts have, so they are technically for Data East, Sega & Stern machines, but can be used for all games as it is simply a small stylistic difference.
Data East/Sega/Stern reference #237-5001-01.