Silver plated. 25.50mm cup diameter with a 0.280" throat bore. The Griego 5 has a more rounded rim on a slightly deeper bowl than a standard Bach 5G. Consistent throughout all registers with lots of middle register overtones. This mouthpiece was designedwith the principal trombonist in mind. Sleek "Deco" style exterior is heavier than traditional models, allowing for a darker, more focused sound.