Flush head sprinklers are quite common in systems from 20 or more years ago. These systems are still very serviceable, and the pop-up flush head is an excellent way to keep them in good shape. The version with pop-up action gives an extra inch or so of spray height which makes it more suitable for grass while a traditional flush head is more common in above-ground applications such as shrubs and flowerbeds. The brass nozzle includes an adjustment screw which allow you to reduce the spray pattern down to 75 percent of its maximum radius of 15 feet. Flush heads have 1/2" female pipe threads (FPT) and you will typically mount them on a 1/2" male pipe thread (MPT) rigid PVC or cut-off riser. The flush head wrench is an accessory which makes it simple to remove and install flush heads without extensive digging. The flush head nozzle is easy to replace with a brass flush head spray nozzle with male threads. These flush heads do not have pressure-regulating riser stems and are not for sale in California and other states which require pressure regulation. Recommended operating pressure is 30 PSI. For outdoor irrigation use with cold water only.