The STH Series design takes high-head Self-Priming Pumps to the next level; hitting heads 20% higher than our competition. The STH design runs at a slower RPM, while providing larger shafts and bearings to support the high head hydraulics. The result is a pump that outperforms the competition in both durability and performance. STH does not require a booster pump to hit heads of up to 253′ with up to 2,000 GPM.