Slightly larger than the 45, this is also a good beginner's mouthpiece. -the manufacturer
Features: • 24.54mm rim diameter • 5.95mm (0.2344" or 15/64") throat • Standard "C" cup • Standard rim • Standard backbore • Standard small shank • Silver plated
California Residents Only: WARNING: Cancer and Reproductive Harm - www.p65warnings.ca.gov