Here are two clock glass/crystals for the Big Ben and Baby Ben by Westclocx.
The first glass is Model 48D fits Big Ben Loud Alarm Old Style No. 48D.
It has a few very small rough spots along edge from manufacturing it won't be visible when installed.
The diameter of Model 48D is approximately 4 1/8"
The second glass is Model No. 61R fits, Baby Ben (convex glass models) Black 61R and Ivory 61S.
These are both genuine Westclox parts.
It also has a few very small rough spots along the edge from manufacturing that will not be visible when installed.
The diameter of Model 61R is approximately 2 5/8".
Please ask if you have any questions.
Thank you for looking.