The screw back button measures about 3/4'' wide. It appears to be in excellent condition as pictured. Below here, for reference, is some additional information on The International Association of Ports and Harbors (IAPH):
International Association of Ports and Harbors
From Wikipedia, the free encyclopedia
The International Association of Ports and Harbors (IAPH) is the global trade association for seaports worldwide. It is headquartered in Tokyo, Japan. Formed in 1955, it is now recognized as the NGO representing ports worldwide. With over 200 ports in membership, as well as numerous national port representative bodies, it now has consultative status with 5 United Nations agencies, including UNCTAD and the IMO.
The IAPH membership is divided into 3 regions, African / European, American and Asian / Oceanian.
The Secretariat is based in Tokyo and is headed by a Secretary General who is appointed by the Board of Directors.