These Wheelock CH70 Fixed candela, Wall mount Chime Strobes provide a low current draw, a choice of single-stroke or vibrating operation, an adjustable sound level, and a chime tone adjustable from 800 Hz to 1200 Hz. They have a strobe listed at 15 cd under UL Standard 1971 and meet 75 cd intensity on axis with low current draw. The strobes can be synchronized using SM (single) or DSM (dual) modules. They also have an attached mounting plate for easy indoor installation on a variety of electrical boxes.