Tested by FDA and SGS, these mugs are made of cellulose extracted from natural bamboo and glass, with strong wear resistance. They are completely biodegradable to protect our land and the environment we live in from ourselves. The bottom of the cup is made of bamboo which allows you to drink a hot drink without burning your fingers. They can be washed by hand or in the dishwasher but cannot be used in the microwave. MINIMUM QUANTITY: 30 PCS