The EVCA - AP - SH Horn / Strobe Series provides a wide range of candela light output options in a single device . The candela settings include a 12 or 24 volt DC operation for the 15 , 35 and 60 ( 75 on axis ) candela settings and 24 volt DC operation for the 15 , 35 , 60 , 75 , 95 and 110 candela settings . The candela setting is displayed through the front window and is selectable using a drum wheel . The horn settings include Temporal , Non - Temporal , March Time and a Chime sound . The horn also has Low , Mid and High volume settings for each pattern and tone . The tones include 2400 Hz , Electro - Mechanical , Broadband and Chime . The voltage input can be either regulated DC or full wave rectified ( FWR ) 12 volt or 24 volt operation with an operating range from 8 to 33 V DC . The strobes can be synchronized using a control panel with an EVCA AP - SMD10 sync module . The EVCA - AP - SH utilizes a universal mounting plate that will mount on a single gang , double gang , octagon and 4 " square electrical boxes . The back plate allows the installer to mount the plate and connect the wire connections . The strobe attaches in a hinge fashion from the top and is secured by a single mounting screw . The strobe completely covers the mounting back plate , therefore it can be mounted before other trades work is completed and not affect the final look .