A fastener is a tubular rivet with internal threads,It can be installed in seconds form one side of the work.Once installed, no finishing work is required on the fastener.The added advantage of not only being a dependable fastener, they are to use with clean threads available for screw attachments,Blind thin sheet materials that are too thin for a tapped thread.Blind Rivet Nuts also are used when an application has little or no access to the backside as they can be installed from the front side of the work piece.Product Name: Rivet Nut;Material: Metric Steel, ZincTypeM8Thread Diameter: 10mm; Length: 21mmGrip Range: 1.0-5.0mm;Body Diameter: 12.9mmApplication hole size: 13mm;Weight: 166gPackage Content: 20 x Rivet NutNote:Light and different displays may cause the color of the item in the picture a little different from the real thing.The measurement allowed error is +/-1-3 cm.