Generally called sit-ups, also called sit-ups. There is also a multifunctional one on the market (that is, you can also practice dumbbells for birds. This kind of board is very helpful for practicing abdominal muscles. There are straight plates and curved plates, which are generally selected according to your own preferences. (However, arc plates are recommended. There are 80~300 in the market, so you can buy them according to your own situation. (Personally, I think I can buy 100~200, and the brand doesn't matter.