Features Prevent Turning: These insert nuts are inserted into a pre-drilled hole by screw in, in that case the external protrusions bite into the wood, preventing the nut from either turning or pulling out. Zinc Alloy Material : These insert nuts are made from high quantity zinc alloy and comes in a resealable transparent plastic box. An insert nut provides a threaded socket for a wooden workpiece, similar to a wall anchor. Operation Guide：Screw-in insert nuts have an external thread and hex socket drive and are screwed in with a hex key wrench.The pre-drilled hole must be as deep as the length of the insert nut plus any portion of the bolt that may be screwed past the end of the nut in the work piece. Advantage Characteristics : Insert nuts are advantageous over barrel nuts and T-nuts, because they can be installed from one side of the workpiece. Different Sizes : This set of screw-in insert nuts come in different sizes and take different screw sizes.10pcs M4/M5/M6*10mm, 10pcs M6*15mm , 5pcs M8*20mm , 5pcs M10*25mm Description: An insert nut provides a threaded socket for a wooden workpiece, similar to a wall anchor. These insert nuts are inserted into a pre-drilled hole by screw in, in that case the external protrusions bite into the wood, preventing the nut from either turning or pulling out. Features: These insert nuts are made from high quantity zinc alloy and comes in a resealable transparent plastic box. Screw-in insert nuts have an external thread and hex socket drive and are screwed in with a hex key wrench. Insert nuts are advantageous over barrel nuts and T-nuts, because they can be installed from one side of the workpiece. This set of screw-in insert nuts come in different sizes and take different screw sizes. The pre-drilled hole must be as deep as the length of the insert nut plus any portion of the bolt that may be screwed past the end of the nut in the work piece. Specifications: Material: Zinc alloy Type: Hex socket screw-in Size and Quantity: M4*10mm         10pcs M5*10mm         10pcs M6*10mm         10pcs M6*15mm         10pcs M8*20mm          5pcs M10*25mm        5pcs Inner Diameter Head Outer Diameter Teeth Average Size Bottom Outer Diameter M4 8±0.2 7.1±0.2 4.7±0.2 M5 9.3±0.2 8.7±0.2 5.7±0.2 M6 11.4± 10.7±0.2 6.8±0.2 M8 12.4±0.2 11.7±0.2 8.9±0.2 M10 16±0.2 14.9±0.2 10.7±0.2 Package Includes: 50pcs x Insert Nuts Package List