The 31-28 is an UHF plug to BNC jack UG-273/U straight RF adapter featuring silver-plated phosphor bronze contacts. Its body is made of brass with a nickel-plated finish, and it incorporates a copolymer of styrene insulator. This adapter is used to connect two dissimilar RF interfaces, commonly in RF communication applications. It has an impedance of 50 ohms, a maximum frequency of 0.5 GHz, and operates within a temperature range of -65°C to 165°C.