For Australian surfers, a 5/4 steamer wetsuit is an essential piece of gear to have in their arsenal for colder waters. It's a type of wetsuit that provides insulation and protection against the cold ocean temperatures, making it possible to surf in harsher conditions. The numbers 5/4 refer to the thickness of the neoprene material used in the wetsuit. The first number, 5, represents the thickness of the neoprene in millimetres used in the torso and legs, while the second number, 4, represents the thickness used in the arms. The thicker material in the torso and legs helps to keep the core of the surfer warm, while the thinner material in the arms allows for greater flexibility and ease of movement. Steamer wetsuits, in general, are designed to keep surfers warm by trapping a thin layer of water between the neoprene and the skin. The body heat generated by the surfer then warms this layer of water, creating a barrier against the cold ocean temperatures. The steamer style wetsuit features long sleeves and legs, making it ideal for colder waters. The term "steamer" comes from the old-fashioned steam-powered boilers that were used to power ships, as the long sleeves and legs of the wetsuit resemble the boiler pipes of the steam engines. Overall, the 5/4 steamer wetsuit is an essential piece of gear for surfers looking to tackle colder waters while staying warm and comfortable.