Made of premium metal, , sturdy, hard, for long time use. perfect for attaching shelf supports and brackets etc when assembling the greenhouse. These bolts are the standard bolt, used in the vast majority of greenhouses. Easily removed and re-used. Necessary accessories for building most greenhouses. Also a good replacement when the parts is damaged. Simply insert the bolt into the groove of the glazing bar and turns to lock securely in place when the nut is tightened., Manufacturer: Jnchdghwa