Made out of thick, durable stainless steel so these mugs are easy to clean and will stand up to regular use for years to come. Welded handle will stay solidly attached. Double-walled mug design provides an air seal which keeps your drink hot up to 8 hours and cold up to 16. When filled with a hot drink, the outer wall will stay cool to the touch. When filled with a cold drink, you won't get condensation or sweating on the outer wall. At 14 ounces, these mugs are big enough to hold an entire can of beer or a large cup of coffee.