This is a nice, 7.5" long spike tooth scarifier, marked "Z-65 C" in raised cast lettering. We assume that is is made to fit sickle bar like a Gravely. We don't know what maker it's for, but the square hole is .5", and the distance from the tapered slot bottom to the nearest point on the .5 square is 3.8". The width of the T-shaped are or the widest point of this unit is 3". There is an interesting saw tooth edges, wear plate intact.