Here is a side by side comparison of the Whitall Tatum CD 153 and 154. You will notice the biggest difference is the 153's dome. The top is near flat and hardly any glass above the pinhole. I would assume this was the fault in this design leading to only a very limited quantity being made. You will also notice that the wire grooves are a little different and that the slope of the outer skirt from the lower wire groove down to the base is different. Hope this helps.