Bright strobe provides ring signaling for deaf and hard of hearing. Ideal for high noise areas. Sturdy construction, commercial quality. Wall mount or place on flat surface. Plugs into RJ11 phone jack. Does not need AC power. White strobe with black letters. Size 4.75"h x 2.5"w x 3"d. Works well on analog phone lines. If using the jack for both phone and signaler, you will need the model with the dual jack adapter.