The first proof strikes, at San Francisco, took place in July. The proof pieces were sold in a plastic holder inside a brown box with a gold eagle seal; the uncirculated silver pieces were encased in pliofilm inside a blue envelope. These were dubbed "brown Ikes" and "blue Ikes" and are still known by those terms. On July 27, 1971, President Nixon presented the first piece to be struck to Mamie Eisenhower at a White House ceremony. Sales of the 40% silver pieces were ended on October 8; the first proof coins were mailed to collectors on October 14, President Eisenhower's birthday.