A glass screw thread with a plastic cap and a silicon washer is a combination of components used to securely fasten a glass container. The glass screw thread is a raised ridge, or series of ridges, on the outside of a glass container that provides a means for attachment to other components.

The plastic cap fits onto the screw thread and helps to protect the contents of the container, as well as provide a stable and leak-proof seal. The silicon washer is placed between the glass and the plastic cap to provide additional sealing and to absorb any shock or stress that may occur during use.

This combination of components is commonly used in applications such as food storage, laboratory experiments, and cosmetic packaging.