Concrete Donuts are designed to be placed around sprinkler heads to protect them from lawnmowers and vehicles. Even when not popped up, your sprinkler spray heads and rotors are at risk; if a lawnmower or car tire runs over them, the pressure can cause the sprinkler head and/or the connecting pipes to crack. Our concrete donuts are constructed of fiber reinforced concrete for maximum strength and designed to fit perfectly around your sprinkler heads.