This 18 inch float measures a full 56 inches in circumference.

It has a clear and complete maker's mark from the Sendai Glass Co.  There is mark WP #6 'Maru Sen' 仙 (aka TY) stamped on the ID seal.

This float float is in excellent condition.  There are no clips; not even a flea bite on the seal button.

I purchased this float from an elderly couple that was stationed in Japan in the 1950's.