Wheelock s loud bell phone ringers are perfect for both Indoor or Outdoor applications. Typical applications would be factories repair shops printing shops loading platforms and warehouses. TelBells utilize a durable high torque permanent magnet motor-driven mechanism and 6 low frequency aluminum bell shell to produce a higher sound output and lower resonant frequency than conventional mechanical bells. TelBells include an extremely adjustable tamper-resistant volume control and are designed for both indoor and outdoor applications.