Material and Finishing The insulated bottle is constructed with superior quality steel and has a copper coating for better heat retention, which makes it very strong and durable. The stylish flask has a contemporary chrome steel finish and is 100 percent rust-free. Fit for Regular Use The temperature retention bottle is ideal for everyday use; gym, jogging or when travelling. This flask maintains your beverage temperature and is quite versatile in use. Easy on maintenance, clean it after use and in spite of extensive usage it will last you forever.