2007 Topps Moments & Milestones is a 193-card set, released exclusively to Hobby outlets, in April, 2007. The set consists of 169 veteran and retired players and 24 cards of eight different rookies.
One of the most bizarrely structured card sets ever produced, each of the 169 veterans has multiple variations based on the player's statistical accomplishments, similar to a mirror insert. For example, Scott Rolen's 2004 NL All-Star season is celebrated with 34 different variations (one for each home run he hit that season) of card #122. Like a mirror, each of the 34 cards is identical to each other, with the exception of a large numeral on the front side of the card. Each individual card is serial-numbered to 150 copies, but when all the different variations of each card are factored in, the production runs are much higher -- there are a total of 5,100 copies of the aforementioned card #122.