The s3A legendary heartbeat / pulse booster box is a Japanese booster box from the Sword & Shield Era. This booster box contains 30 packs and every booster pack has 5 cards in inside. Together with the s4 Electryfing Tackle or Shocking Volt Tackle box this is about the same as Vivid Voltage of Sword & Shield in English. What makes this set unique is that it is the first time Amazing Rares are available in the reverse slot of a pack. Every booster box usually contains 2 amazing rares.