Even though the United States Mint ended production of 90% silver dimes, quarters and half dollars for general circulation in 1964, the Kennedy half dollar continued to have some silver content all the way through 1970 (reduced from 90% to 40%), while dimes and quarters did not. Dimes and quarters contained no silver at all starting in 1965, whereas Kennedy half dollars didn’t become “non-silver” until 1971. The term “40% silver”, when it refers to half dollars, is generally understood to mean coins dated 1965 thru 1969, even though 1970-dated half dollars are also 40% silver. This is because half dollars dated 1970 are scarcer and therefore usually worth somewhat more than their 1965 thru 1969 counterparts; the U.S. Mint didn’t release 1970-dated half dollars into general circulation – they were available only in Proof Sets or Mint Sets purchased from the U.S. Mint, and thus their additional value.
For the 1976 Bicentennial, the U.S. Mint again introduced 40% silver coins, but as with 1970 Kennedy half dollars, these 40% silver coins also weren’t released into general circulation – the Mint offered 3-piece Proof Sets and 3-Piece Mint Sets for sale to the public, containing an Eisenhower Bicentennial silver dollar, a Kennedy Bicentennial silver half dollar and a Bicentennial Washington quarter, all of which were made of 40% silver (the Mint also made non-silver versions of all of these coins as well).
This product you are viewing will consist of primarily 1965 thru 1969-dated Kennedy half dollars, although you might also find an occasional 1776-1976 dated Kennedy half dollar as well. All coins you receive, regardless of date, will be made of 40% silver.