This weathermatic 170-0855sa, outdoor transformer is compatible with the Pl1600 & Sl1600 controllers. Weathermatic products are designed with efficiency in mind. The typical a1/2-acre commercial property uses about one million gallon of landscape water per year. On average, properties exceed the landscape watering need by about 38% - or 380,000 gallon. Many properties overwater by as much as 60% - pouring hundreds of thousands of gallon of clean water into our streets & sewers. Weathermatic's primary goal is to reduce over watering wherever possible.