This year, the Beijing University of Chemical Technology (BUCT) printed its admission letters on an innovative carbon fiber composite material that is just 0.2 millimeters thick but as sharp and strong as a knife.

While most university admission letters are usually put away in a cupboard after students learn they have been accepted, freshmen accepted by the Beijing University of Chemical Technology have been busy using their admission letters as a multi-tool. Many of them have been sharing videos of themselves using the sturdy admission letters to cut all kinds of fruits, even melons, mincing pieces of meat, and holding them over open flames to prove they don’t burn or melt. After several of these videos went viral, a spokesperson from the Chinese university went public to clarify that this year’s admission letters were made out of an innovative material developed at the learning institution.

“The carbon fiber-made admission letter not only showcases our university’s exceptional abilities in the field of carbon fiber composite material but also marks the transformation of China’s homegrown carbon fiber composite material from high-end industrial use to daily application,” Yang Xiaoping, a professor at BUCT’s College of Materials Science and Engineering, said.

Measuring only 0.2 millimeters in thickness, the coveted Beijing University of Chemical Technology admission letters are very flexible but tough enough to cut through watermelons, as demonstrated in multiple viral videos on Chinese social media. The letters have come to be known as “invincible” online.

While proud of its innovative carbon fiber material, BUCT has urged freshmen who received admission letters to stop abusing them by staging dangerous experiments ,and instead cherish them.