These regulators are used in all irrigation systems. They easily install inline and have a built-in indicator when proper outlet pressure is achieved. The low flow model has a 3/4 inch female inlet and outlet. The high flow model has female inlet and male outlet. The low flow is rated at 0.25 - 4.4 gallons per minute and the high flow is rated at 4.5 - 17.6 gallons per minute.