A ferrite toroid ring core is a type of core that is commonly used in inductors, transformers, and other types of electronic components. It is made from a ferrite material, which is a type of ceramic that is known for its high magnetic permeability and low core loss. The core is shaped like a toroid, which is a ring with a hole in the center. The size you mentioned (22x14x8mm) is the outer diameter, inner diameter, and height of the core respectively. The color green indicates the type of ferrite material used and it is a standard size that can be used in many different applications.

These Toroid Ferrite Cores designed with 14mm inner diameter, 22mm outside diameter, 8mm height.
Used widely in power transformers, current transducers, instrument transformers, inductors, chokes, ballasts, voltage stabilizers and regulators, welding transformers, broad band transformers, filters, etc.