This bluetooth speaker is made of 304 stainless steel, which is rust-proof, lead-free, durable, sturdy and reusable. And with double wall vacuum insulation design, hot drinks can be kept warm for up to 6 hours and cold drinks can be refrigerated for up to 12 hours. There is a detachable wireless speaker at the bottom of the cup, you can enjoy music and relax while drinking water. Customized logo is available.