There are a number of differences between the Novelty / Elmer Glass Company and Brookfield made STAR baby signals.

1) Novelty / Elmer typically has an "Elmer ring" at the top of the pinhole. The Brookfield never does.

2) Novelty / Elmer typically has a very flat base to the inner skirt. The Brookfield is always rather rounded on the outside edge of the inner skirt.

3) Novelty / Elmer never has any indication of vent drips on the inner skirt. The Brookfield frequently does.

4) Novelty / Elmer typically come in light blues and various greens. The Brookfield comes only in the typical post-1908 dark aqua. Note that none of the Novelty / Elmer colors match any of the Brookfield greens and blues.

5) Novelty / Elmer comes in a relatively small range of slightly different profiles, not really matching the Brookfield. The Brookfield only comes in one, matching the profile of the CD 160 B NO 32.

These are based on my observations -- if you have seen anything contradicting these observations, I'd be very interested in hearing about it!