美国采购需求：豪华音乐机芯，弹簧驱动微型音乐机芯，标准18音符，标准18音符音乐机芯

I came across your product listing and noticed that you refer to a "plastic shape." I'm keen to understand more about the materials used in the music wind-up mechanism. Specifically, does this indicate that the mechanism is made of plastic instead of metal? This detail is crucial for my evaluation, as I'm looking for quality and durability in these components. Additionally, if you could provide further insights on the overall design, functionality, and any testing standards the product meets, that would be greatly appreciated. Understanding the material composition and performance will help me make a more informed decision moving forward. Looking forward to your clarification!