Lockers are usually physically joined together side by side, and are commonly made by steel. Lockers are usually in outdoor locations near railway stations, department stores and the like where people may want to store goods securely.
Heavy-duty or high-security lockers are similar to the standard models, but are usually made from thicker steel. Some models are made from steel 1.2 mm. thick, in contrast to the more usual 0.8 mm.