Used Shilke Trumpet Mouthpiece 8A4
Shilke 8A4. The cup size is slightly funnel shaped. It is their smallest and shallowest cup. The rim diameter is 16.25 millimeters (0.640 inches). The rim contour is 4 or "semi-flat". It has the standard Shilke backbore. See https://trumpet.biz/trumpet-mouthpieces/trumpet-mouthpiece-guide/ for more information on Shilke mouthpieces.