Sprinkler

This sprinkler, an "Impact Sprinkler", pivots on a bearing on top of its threaded attachment nut, and is driven in a circular motion by a spring-loaded arm that is pushed back by the water stream, then returning to "impact" the stream. This produces an intermittent diffusion of the stream that provides a uniform waterfall closer to the sprinkler. The uninterrupted flow path of impact heads makes them less vulnerable to damage and clogging by dirt and sand in the water, making them suitable for systems running on well water. One defining feature of impact heads is that they almost always have a male pipe thread, as opposed to the female threads found on virtually all other sprinkler types. The sprinkler head was originally manufactured from metal, though since the 1970s they have also been constructed from thermoplastics for improved corrosion resistance.