Hunter Institutional Spray Series Hunter Institutional Spray Series Sprinklers are rugged, water-saving sprinklers designed for commercial, institutional, and public area applications. The Institutional Spray series features a Positive-seal flush cap, Pressure-activated wiper seal, True pressure regulation, In-stem regulator, Super heavyduty check valve assembly and the most powerful retraction spring in its class. All this and they also carry a five year warranty.