This is a Schilke M3 Symphony trumpet mouthpiece. Silver.

Cleaned and silver polished. It is a used excellent condition piece for trumpet and was given to me by Ginger Turner. We both played on it for a bit. I eventually landed on a slightly smaller 25 throat and 17mm cup in a Wick 1.5C, but this mouthpiece is very close to that and served a community symphony well. It's great on a C trumpet. See below.

Condition is good, plating is 98%. The throat is clean with one tiny scratch, and the backbore clear and smooth. The rim feels smooth and good. This is a fine choice for a orchestral work. It is not a jazz piece as the cup is deep and squarer than most Schilkes, almost Bach like, so Medium Deep depth.

Specs:

Cup Diameter 17.05 mm

Throat Drill #24. (0.152in) This is larger than the Bach 27 series (0.144), or the Schilke 26 standards (0.147in), and allows incredible volume and projection with little resistance.

Rim: 3C like (Std), a regular 14/15 Schilke rim that is optimal compromise for flexibility and endurance.

Manufacturer page https://www.schilkemusic.com/products/mouthpieces/trumpet/#symphony-series