Cat vaccine needles are used for 2.5 cm, and the syringe is 2.5 ml. The color of the needle is orange, red, etc.
The syringe is a common medical appliance, as early as the 15th century, the Italians Catinel proposed the principle of syringe. It is mainly used for injecting medicinal fluids or pumping liquids. Syringes can also be used for medical devices, containers, such as some chromatography in the scientific instruments injected through the rubber diaphragm. Injecting gas into a blood vessel will result in an air embolism. Air is removed from the syringe to avoid embolization by inverting the syringe, tapping it gently, and squeezing out a small amount of fluid before injecting into the bloodstream.