The syringe is designed for use on both a space-flight to Mars, and for use on Mars. The syringe is 3mL (each marking for 1/2 mL), but could be scaled to other sizes. The cylinder on the right side is the needle disposal container. Using the threads, one screws the syringe in, opens the small window, and removes the needle. Then, a stopper can be screwed in, or the syringe can be stored in that manner with the needle disposal for convenience. This was designed because pointy medical objects like needles are very dangerous in space, and must be handled with the utmost precaution.