Specification:

Size: Ring 17.5-7.5x3  Fe   
Outer Dia:17.5mm
Inner Dia:7.5mm
Thickness: 3mm
Grade: Y 30
Color: Black
Max Operating Temperature: 300°C   

Description:
Ferrite also is known as Ceramic Magnet is a Composition of iron oxide and barium or strontium carbonate. These materials are readily available and at a lower cost than other types of materials used in the making of Permanent magnets.