Sneaky Pete says:

Complete your V.A.S. (Vaporizer Accessory Stand) with a Round Top or Flat Top Glass Stopper.  Made from borosilicate glass, the Glass Stopper allows you to fill the reservoir arm with isopropyl alcohol and will prevent the alcohol from evaporating. Isopropyl alcohol is the ultimate cleaning solution for all of your vapes and accessories, so keep it close at hand at all times. Vape enthusiasts know the V.A.S. is the perfect accessory for all of your desktop organizational needs, and the Glass Stopper will give even more utility to your setup.