✍️Wendy Brown, Lic. Ac.
Unsurprisingly, some people initially express some concern about needles that are used in acupuncture treatment. On occasion, the concern may verge on a phobia of needles in general, which would likely deter the person from seeking acupuncture treatment that they may derive great benefit from, due to a vague and undifferentiated grouping of needles, and how they were applied. Here is an important visual to lend perspective to the extent to which acupuncture needles are finer than needles that people may have previously encountered. 
Used for acupuncture, needles are almost exclusively constructed of stainless steel (although infrequently, of zinc, gold, or copper). They are pre-sterilized, fine-gauge, with no hollow space to transmit or extract a liquid substance. Acupuncture needles are inserted to varying depths from shallowly beneath the skin to a depth that depends upon structural location and patient’s personal build. The needles used are usually silicon-coated to create an extremely smooth blade surface, and they are completed with an ethylene oxide gas sterilization which can keep individually packaged needles sterile for approximately 5 years. Needle gauge, or thickness, and needle length vary considerably depending upon factors from anatomical terrain, to patient comfort level, to desired outcomes of treatment, most commonly. Nearly all acupuncture needles are intended for single use and are to be disposed of in bio-hazard waste containers, and discarded accordingly.
There is a Chinese phrase:
