Experts declare which is better, a3 riding binding or a4 binding?

experts declare that a3 riding is bound. A3 riding binding can be opened at 18 degrees, which is convenient to set. a4 binding will encounter some resistance when it is completely opened, making it flat is not easy, the cost is expensive, and the binding process is troublesome. A3 horse-riding binding refers to a method of book binding, such as mounting on horseback, that is, after the book is thinly covered, it is placed on the iron frame to thread the iron wire nail, and a4 glue is equipped with a professional glue loader.