Medium Rubber Toughened (300 cps) is a medium grade Black EthylCyanoacrylat adhesive. The rubber compound imparts a bit of flexibility giving higher peel and shock resistance than the clear grades. It has been formulated to achieve the strongest possible bond in a one-component, solvent-free adhesive that does not require a catalyst, heat or clamps. We have extensively tested this adhesive and continue to be amazed at its holding power. E-Z Bond Cyanoacrylate Adhesives also known as "crazy glue" have fast setting, high flowability and good penetration characteristics. They are a clear one-component, solvent-free system that does not require a catalyst, heat or clamps. When two surfaces, applied with a thin layer, come into contact, atmospheric moisture produces a rapid polymerization with outstanding bonding.