This is a nozzle for use with swimming pools that have plumbing for sprays from the side of the pool over the water. It screws into a standard PVC 3/4" threaded fitting. There are 3 spray exits and it forms a nice pattern in the water.
This may be a tight fit on the threads and if so scale to 97%. Orient as shown in the photo.
The author hasn't provided the model origin yet.