Phoenix Contact 2909741 A pre-assembled relay module is a compact assembly consisting of a relay base, function plug-in module, power contact relay, and retaining bracket, designed to meet the safety standards of ATEX/IECEx certification for Zone 2 environments, Ex Zone Class I, Div. 2, with features such as push-in connections, four changeover contacts, freewheeling diodes, and an input voltage of 24V DC.