Made in the United States from 100% USA stainless steel, Self aspirating syringe is all one part and holds 1.8cc. Lightweight and features a comfort fitting thumb ring that provides a secure grip for multiple hand sizes. The self-aspirating mechanism works by a little bump at the end of the syringe compressing the diaphragm of the anesthetic cartridge during injection. When the pressure of injection is released there is the relaxation of the diaphragm, thus creating negative pressure. In self-aspirating needles and syringe system, aspiration can occur only after injection has been started.