The 4 Key Rookie (RC) Stickers are Aaron Ekblad, John Klingberg, Nikita Kucherov and Evgeny Kuznetsov. This was the largest collection of NHL hockey stickers in history beating out last year's 500 sticker collection. There are 516 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.