The Jupiter 1604S Tribune XO Series Professional Bb Trumpet is the large bore equivalent of the 1602S XO Series. The 1604S XO Series features a .462-inch bore with a 4.8-inch one-piece hand-hammered bell for excellent response and tone that is free blowing. The 1604S Series includes both a rounded and elliptical main tuning slide plus regular and light action spring sets to customize the response of the instrument. The 1604S XO also includes standard and weighted bottom valve caps for added mass to enhance the projection of the instrument.