Milton Driveway Signal Bell has a 6" diameter and operates on 110 volt electric. Offering an instant signal every time a connected hose is depressed, the signal bell produces a ring louder than that of the model 802 signal chime, intended for garages, kitchens, & other locations where volume is an issue. The use of Milton's patented signal hose and a hose anchor is also recommended, though all are sold separately.