The Hydro-Rain 54550 HRS 200 Pressure Regulated Adjustable Shrub Adapter is an accessory component for the HRS 200 irrigation system. This system is used around the world in commercial, municipal, and residential applications. The patented adjustable pressure regulator feature allows you to select 30 or 40 psi pressure regulation. This spray head is also compatible with most female-threaded nozzles on the market.