How to read product dimensions
Distinguish overall length, insertable length, width, and base size.
Keep measurements separate
The Dr. Skin Dr. Samuel lists seven inches overall and five inches insertable. The base can account for some of that difference. A width number also means something different from circumference.
Ask for the missing figure
Product titles sometimes give a length without specifying how it was measured. If the published size is incomplete, confirm the exact variant and the measurement you need before ordering.