When coins are being struck, the lower die (reverse die) is surround by a collar. This collar floats on springs, which prevents damage to the coinage press if there is a malfunction. When the planchet is feed into the coinage press, it should rest inside the collar on the reverse die (anvil die).

If the planchet does not rest completely inside the collar, you will have an Off Center struck coin. Only part of the coin will show the design. Since the collar floats beside the die, it is pushed down if the planchet is resting on the collar during the striking process.

To be an Off Center struck coin, both the obverse and the reverse must be equally off center and part of the design elements must be missing. If only one side of the coin is off center, it is a MAD (MisAligned Die).

This is an off center stuck Jeffererson Nickel.

When two planchets lay on the anvil die and are both struck by the same die. The example on the right is called a Chain Strike Lincoln cent. The odds against finding both sides of this Chain Strike are astronomical.

The number of people that collect Chain Strikes is very limited, mainly because of their rarity. But when one comes up on an auction, bidders come out of the woodwork to bid on one of these gems.