The 2021 Topps MLB Series 1 Baseball Hanger Box is a factory-sealed sports trading card box that contains 67 cards. The cards are made of card stock and feature players from Major League Baseball (MLB) teams such as the New York Yankees, Los Angeles Dodgers, and Boston Red Sox. The box includes cards of popular players like Juan Soto and Ronald Acuña Jr. and features serial numbered, short print, base set, rookie, parallel, insert, and chase cards. The cards are from the 2021 season and are manufactured in the United States by Topps.