Wheelock MB Series 24V Motor Bells provide a better engineering motor bell for fire and life safety alarm systems. Wheelock Motor Bells are perfect for industrial uses including schools, hospitals, and commercial buildings. The Wheelock Series MB Bells include higher dBA, low current draw, built-in trimplate for semi-flush mounting, low frequency aluminum shells, and low RFI noise. The motor for Series MB Bells is a durable, high torque permanent magnet motor selected for its high performance and long life. These DC vibrating Series MB Motor Bells are offered in 6 and 10 shell sizes in both 12 and 24 VDC models.