This is a Melnor brass head pulsating lawn sprinkler model 9635C.
The adjustable sprinkler waters in a circle up to 80ft.
It measures 12.75" long and 4.5" wide at the head, and fits on a 1" diameter hose.
This sprinkler is in pre-owned condition with a small amount of corrosion on the back of the original card with the instructions.