Apollo Visual Indicator Base is a loop-powered visual indicator combined with a standard Intelligent mounting base. It is used to signal a fire alarm in enclosed areas. It can be used with either a detector fitted or with a cap as a stand-alone alarm device. The base is loop powered and normally pulled by its individual address. It is supplied with a built-in isolator. It responds to its own individual address set with a DIL switch, it also responds to a group address, set by means of a four segment DIL-switch and to a synchronisation address which is embedded in the unit. Addresses 1 to 111 are used exclusively for individual addresses, addresses 112 to 126 may be used as individual addresses but only if the four segment DIL-switch is not used, that is group addressing is disabled. If the four segment DIL-switch were set to any number other than the default 127, a pre-set analogue value of four would be transmitted to indicate a fault. It is recommended that the synchronisations address 0 is set by the control panel at regular intervals to align the internal clock to all visual indicator bases. The result is that the visual indicator bases are synchronised with each other when activated. It is made of white flame-retardant polycarbonate and translucent flame-retardant polycarbonate diffuser.