The 4 Key Rookie (RC) Stickers are Nathan MacKinnon, Johnny Gaudreau, Frederik Andersen and Tanner Pearson. This was the largest collection of NHL hockey stickers in history. There are 500 physical stickers to collect in this set. There are 2 versions of the album made for this series. One version features Canadian players and the other features the American stars. Each sticker measures 4.9 X 6.9 cm (1.9 X 2.75 inches) which reverts back to the early 80's classic size of sticker.