What's the difference between a big needle and a small needle in acupuncture?

According to the traditional view, acupuncture needles are half an inch, one inch, one and a half inches, two inches and so on. Some acupoints, such as loop jump, may need 3-3.5 inches of needle to stab; But according to the modern standard notation, the unit of "0.30x30" is mm, the front 0.30 is the thickness, and the back 30 is the length. The length of the needle is used in different parts of the surgery and is unlikely to be replaced. Generally speaking, long needles can replace short needles, but the penetration depth is small; In some cases, short needles can also replace long needles, which requires the operator's skill to be very strong and easy to achieve, and requires a lot of manipulations and gases to achieve its pathogenic effect; In addition to thickness, there is also this feeling in clinic. The thicker the needle, the easier it is to operate, but the greater the pain of the patient. On the contrary, the thinner the needle, the higher the operating requirements, the more likely it is to cause the needle to bend. The higher the requirements for the operator, the less the pain for the patient, but it is really tiring for the doctor.