There are many features in the bamboo bat and the mouth!
Although we are pushing for bamboo bat training every day, we can see what the bamboo bat of ball park dotcom actually has. This paper introduces the size of each size from time to time, and here is a diagram of the characteristics of the whole bamboo bat!
This is the ballpark dotcom bamboo bat.
More information about bamboo bats checks the Ballpark Dotcom website!
Training Bamboo Bats https://japan-ballpark.com/collections/training-bat.html