The ILI-1, ILI-1A, ILI-1B, ILI-1H, ILI-1AH, ILI-1BH are plug-in, two-wire ionization detectors, compatible with Fire Safety IXL, MXL and XL3 control panels. The ILI Series ionization detectors consist of self-compensating dual ionization chambers and highly stable solid state electronic circuitry.