I recently purchased this Brookfield signal at an antique shop in Vermont because it looked a little odd. The wire ridge is sharp to the touch, not round. The mold line stops just below the wire ridge. The dome is relatively flat and it's topped with a small, off-center, nipple. I'm pretty sure this is a CD 133 [470]. 3 7/8" tall and 2 3/4" wide. Does anyone know why this piece has a sharp wire ridge?