This is a Denis Wick 4L short cornet mouthpiece. There are some areas where the gold plating is worn. It seems to be suitable for instruments of a specific era, but the details are unknown. When I used it myself, I used it with a Brasspire Unicorn short cornet. (Although I'm not certain, I feel like it would fit short cornets from manufacturers like Yamaha.) Please feel free to ask any questions!