The clamp includes a high strength alloy Boss Head for securing the clamp to a frame or other apparatus. The Boss Head will accept a rod diameter of 18 mm (approximately 11/16″). The screw adjustment allows for precise pressure when gripping glass objects, to avoid potential breakage. Swivel between Clamp and Boss Head. Clamp is constructed of powder coated high grade zinc alloy. Due to the cork lining it is not recommended that the prongs of the clamp are placed in direct heat. Ideal uses for beakers, Erlenmeyer flasks, test-tubes, boiling (Florence) flasks, burettes. Eisco Labs proudly manufactures its own products using state-of-the-art equipment, and following the highest standards of quality control. Each product is carefully designed by a team of laboratory professionals and experienced engineers with quality and durability in mind. They are manufactured with only the highest grade, raw materials and according to international quality standards to ensure that they can withstand use in even the toughest laboratory environments.