Double wall 18/8 stainless steel thermal bottle with copper vacuum insulation, threaded stainless steel dual-opening top, and lid retaining loop.
Hot: 8 hours
Cold: 16 hours
Superior Insulation -
The copper plating on the inner wall is an extra line of defense against temperature transfer. Heat escapes much slower so your hot coffee stays hot even in a snow storm, and heat enters much slower so your ice water doesn't melt even under a blistering summer sun.