This keychain has a Miraculous Mary charm on it. It is made of pewter. The ring is 25 mm in diameter. The medal is 2.5 cm tall and 1.5 cm wide or about 1" by 5/8". The photo shows what the front and back looks like, but you are buying one.
I also have several other keychains in my ebay store including official licensed college and university keychains and charms.