When a home run reaches a level of the stadium above the first section of box seats in the outfield, it is called an upper decker. Some ballparks offer both a second and third deck of seats above the box seats, thus an upper decker could be a home run that reaches the second or third deck in a given stadium.
Only the strongest home run hitters can launch upper deckers, although some less powerful batters have reached the upper decks a few times in their career when they make unusually solid contact with the ball. This results from a batter taking a home run swing and often guessing correctly as to what pitch is coming. Pitchers who throw especially hard can be vulnerable to upper deckers as well because the batters simply transfer their velocity from the pitch to the batted ball. Upper deckers draw lots of oohs and aahs from the crowd as the ball soars far past the lower level of seats in the outfield up into the nether regions of the ballpark. Notable upper deckers include Reggie Jackson's launch in the All-Star game and . Some ballparks even feature a different seat color for certain upper deck shots that traveled far beyond the average home run.