On the left is a regular CD 1053 spool, and on the right is the "hex top, lag bolt" variant. Clearly quite different! Now, imagine putting a wrench on that hex top and torquing it down... I can't imagine how the glass wouldn't shatter... Probably why this was never a production item! Both are Hemingray products. UPDATE: The insulator on the the right has been reassigned CD 1034 so that it fits into the service insulator with lag screw CD range.