what are hockey puck made of?
<answer> Vulcanized rubber <context> Background. Hockey pucks are flat, solid, black disk-shaped objects made of vulcanized rubber. Regulation National Hockey League (NHL) pucks are black, 3 in (7.6 cm) in diameter, 1 in (2.54 cm) thick, and weighing 5.5-6 oz (154-168 g). The edge has a series of diamonds, slightly raised bumps or grooves.