I have rice filled conditioning bag is it good for improve knuckles ? Or do I need make new one with mung beans ?
I no longer condition the knuckles, because I wondered why I needed to condition them in the first place. As a rule of thumb, fists are considered "hard", and hard should strike soft, while soft should strike hard.
Given this concept, the only purpose for such conditioning is to have the fist strike something hard - like the skull or jaw, and usually, this isn't very safe to do. In any case, if you're young, you can probably get away with it. But when you get older, you find better ways to strike that require no conditioning. Punching the stomach, for example, does not require knuckle conditioning.
Having said that, my older days of knuckle (and fingertip) training used mung beans because the oils in the beans would help keep the hands from drying out. Rice was taboo because it would rob your hands of moisture (it's commonly added to salt shakers to do just this!)
Now I can open the link which is of a bag made out of duct tape and filled with either mung bean or rice. I wouldn't use either for conditioning, that's not how you condition knuckles. We would fill a large pot filled with mung bean and punch the dried out mung beans. But the idea of conditioning knuckles at all is questionable at best.