This support ring is simple in structure, strong in support, easy to use in laboratory, factory and other occasions. Made of quality iron, ensuring it is durable, corrosion resistant and sturdy constructed, which is the best choice for your workbench. Features - Color: Black. - Material: Iron. - Inner diameter: 55mm, 66mm, 104mm. - Fine craftsmanship and exquisite details ensure its practicality and popularity. - This laboratory ring is made of high-quality metal material for durability. - Adopts precision production to the stable characteristics and high reliability. - These laboratory rings are very nice laboratory assistants and very practical. - The advantages of this laboratory closed metal ring is oxidation resistance.Package List3 x support rings