Authentic Japanese glass fishing float with mark WP #3 'Kita' 北 or more commonly known as FF. It's the company trademark for Hokuyo Glass Company.
It has a well-centered stamp on the seal button.
This float comes in one of my favorite sizes 7 inches. I like these 7 inch floats because they display so well. It measures 22 1/2 inches around.
Excellent provenance having come from the ex-Ramon Fulton collection.