The Metcal 700 natural syringe barrel. Developed with a blend of high quality silicone and chloride-free polypropylene, it provides high accuracy and stability. The unique ultra-low construction of the syringe barrel inner diameter yields high accuracy and stability. - The syringe is comprised of industry compliant silicone and chloride free, low friction polypropylene. 3 Colors - natural for most generic applications, amber for protection of UV/visible light block (upto 520nm), black for total light block.