PURE COPPER - No nickel, tin, or other metals on copper mugs! Only pure copper to give your moscow mule the right taste. PERFECT SIZE - 16 oz. size just like the original copper moscow mule mug. Not too large nor too small LATEST TECHNOLOGY, NO RIVETS - Rivets basically need holes to screw on the handles, so they leak after a while. Advanced Mixology uses the latest metal joining technology to get a no rivet joint TARNISH RESISTANT - Coated with food grade lacquer on inside and outside to retain its shine. LIFETIME WARRANTY - To demonstrate our confidence in the quality of our mugs we offer a NO QUESTIONS ASKED 100% REFUND GUARANTEE. If you are not happy for any reason, just let us know and we will immediately give you a refund. Don't trust us? Just look at our near perfect reviews.