Clipped planchets are a really neat error and often quite accessible even for collectors on a limited budget. Each individual planchet (blank) for coins are stamped out of a strip of the relevant alloy prior to undergoing the minting process. Occasionally these blanks are struck at the end of the sheet and can be incomplete. As a result we are given an incomplete blank with a "clipped" portion missing.

1944 Penny

Weight	9.45 grams
Composition	97% Copper, 2.5% Zinc 0.5% Tin
Grade	Extremely Fine