This is a neck screw for a saxophone. I used it on a Yamaha YTS-82ZS for about six months after purchasing it. In my subjective opinion, the blowing feel was slightly lighter than the original, and I felt that the instrument resonated well and was easier to play. For size reference, I've uploaded images comparing it with the Yamaha original in the 4th and 5th photos. As you can see in the images, there is some aging, so please consider this before purchasing. Feel free to ask any questions in the comments. ※ The following is borrowed from the previous owner's description: "I've forgotten the name, but it was made in a workshop and not a mass-produced item from a major manufacturer. It's a luxurious special edition with a phosphor bronze screw that has been silver-plated and then gold-plated. The screw pitch is 0.7, so it can be used on Yamaha YAMAHA and Keilwerth saxophones. The sound was undeniably excellent thanks to the plating, but the blowing feel was slightly lighter than the original, and since the ASP already resonates well and has a light blowing feel, I was using the heavier original screw. I especially recommend it to those who find their instrument difficult to resonate or feel that the sound quality is stiff and the blowing feel is heavy. Conversely, it may not be suitable for those who want to focus the sound and make it tight. I've also played the screw that Super Player Masato Honda mentioned on X the other day, and this gives the impression of being a higher-end version of that. It's almost new, as I only tried it once."