"This kind of hardcover book is always like this," He Ao had completed the transfer and took the book from Roger's hands, "The inner layer of the cover uses cardboard, and the outside is covered with a layer of calfskin, fabric, or thick paper, which makes it easier to preserve and look more expensive."
He Ao flipped through the book in his hands, "For example, the cover of this book is cardboard covered with a layer of printed thick paper."
"Every trade has its tricks."
Roger laughed.
Then he led He Ao outside to the shopfront, took out a black metal object about one centimeter wide and two centimeters long, carved with cloud patterns, from a drawer, and threw it to He Ao.
"What's this?"
He Ao caught the metal object and pressed it lightly, and three metal contact points slowly emerged from one end of the metal body.
