The clad circulation strikes of the Eisenhower dollar, the largest clad coin ever issued by the US Mint, were available to the general public through banks beginning on November 1, 1971. Many were hoarded by collectors; there was initially sufficient demand for the coins that many banks imposed a limit of one coin per customer. The clad pieces were struck from coinage strip purchased by the Mint from contractors. Many were not well-struck, causing collectors to purchase rolls in search of better specimens. An oily film was found on a large number of the coins; these coins were cleaned by collectors.