"Doubling Time" Message & Equation on Blackboard Coffee Mug

Give a made-to-order mug from Zazzle to someone special, or treat yourself to a design that brings you joy or makes you laugh. Create your own photo mug, shop our collection of the funniest joke mugs, personalise your mug with a monogram, or express yourself with one of our 10 million designs.

• Available in 325 ml or 443 ml
• Dimensions:
  • 325 ml: 8.1 cm D x 9.7 cm H
  • 443 ml: 8.6 cm D x 11.4 cm H
• Microwave and dishwasher safe
• Use caution when removing the mug from the microwave. Use a pot holder or glove as necessary if it is too hot to the touch. Do not microwave an empty mug
• Strong, ceramic construction
• Meets FDA requirements for food and beverage safety
• Do not overfill and be careful with hot liquids that may scald
• Keep out of reach of children when filled with hot liquid