When about millions of times begin to keep the horizontal, and it exceeds 10 million times, this becomes the horizontal. When this frequency is exceeded, this becomes permanent longevity.
● → sign is an unbreaking.
First of all, when the steel belt is examined, this numerical value is designed for aiming. The standard of this numerical value is 700 times. The bend frequency is assumed to be 600,500 when few. In this case, meeting is required.
Title: Steel Belt (21)
