This single hole 17mm light green atom is not supplied with any of the standard sets but is available for sale as a standalone item. It is intended for use as the "4th" halogen so that chlorine, fluorine, bromine & iodine can all be identified separately.
Use only these genuine Molymod Atoms & Bonds for full compatibility with any of our Molymod Molecular Model Sets & Molymod Molecular Model Kits.