This CD 101 is kind of short in stature for one of these. It has 3 of these "small" bubbles around the skirt. With the pinhole cranked to the dome, this one may hold the record for the least amount of glass used to make a pony insulator. With glass as thin as it is in the bubble areas, it is a wonder it survived shipping, handling, years in service, and whatever came after to be with us today !