The Edwards 2453BSA Series Bell/Strobe Adaptor Plate contains a 30, 15/75, or 110 candela strobe. The unit is specifically designed for use with the 439D‑AW‑R series of 6" (152mm), 8" (203mm) and 10" (254mm) red fire alarm bells (ordered separately). The Adaptor Plate is available in red. The strobes employ a unique microprocessor design that assures all units operate at the same time and at a rate of one flash per second thereby reducing the risk of causing disorientation of a small portion of the population having photosensitivity. Wire leads are provided for easy installation of the strobe. The units are rated for indoor use. The strobes require a continuous (non‑pulsed) DC source.