STHL YA11-1-D-29-RN YA11 SERIES AUDIBLE ALARM BUZZER, HAZARDOUS LOCATION RATED, 100 DB AT 1M, 2.5 KHZ TO 3.1 KHZ TONE FREQUENCY, ALTERNATING TWO-TONE TONE(S), 24 VDC, PANEL MOUNT, ALUMINIUM/ABS PLASTIC HOUSING, RED, IP66, NEMA 4X.