Brownie crystal receiver and pair of Lissen headphones, made by the J W B Wireless Company and Lissen Limited, London, England, 1924-1927.
Crystal radios were the cheapest a simplest form of radio available in the 1920s. It didn't require a power source, instead running on the power generated by radiowaves. This little radio set was designed to be used exclusively with headphones. It could have two pairs of headphones attached as standard, with an adaptor available to enable more sets to be added. However, a common way to save money was to put the headphones in a mixing bowl, to distribute the sound to the whole family.