The Easy Dial indoor sprinkler timer/controller is the simplest way we know to control 24 VAC sprinkler systems with up to 4 zones/stations. This timer is engineered for installation in an indoor location, meaning a covered place that is not exposed to water. You can use it in an outdoor location if you place it inside an Orbit outdoor cabinet. The A and B program slots allow you to set up to two unique watering schedules tailored to different types of zones in the yard. Each program has space for four different start times, which allows you to create cycle and soak windows that encourage water infiltration into the soil. The Easy Dial sprinkler timer automatically "stacks" overlapping runtimes from different programs so that only one solenoid runs at any given time. The manual run feature lets you run one zone, select zones, or all zones for a specified length of time — convenient for zone testing or supplemental watering. The rain delay feature lets you skip watering for 24, 48, or 72 hours when Mother Nature handles it, and a sensor port lets you add an automatic rain and freeze sensor (sold separately). Water budgeting adjusts every run time from 10% to 200% in one step, so you can dial the whole schedule up or down as the seasons change. Installation is as simple as mounting the timer on the wall, putting the common wire (typically white) in the C terminal and the individual zone wires in each numbered station terminal, plugging in the transformer, and setting the schedules. Screw terminals hold the sprinkler wire securely in place. The recommended standard sprinkler wire for this timer is 18 gauge with 5 or 7 strands.