Metric thread,corrosion-resistant environmental protection.threaded inserts for wood.More Usage and Install: pre-drill a proper hole, screw-in with Screws Threaded Inserts. Fastener Connector Hex Socket Drive Threaded Insert Nuts For Wood Furniture Assortment.Applications: These furniture screws are suitable for furniture hardwood/ solid wood, for furniture combinations.Features of insert nut: These threaded inserts are inserted into a pre-drilled hole by screwing in, in that case the external protrusions bite into the wood, preventing the nut from either turning or pulling out.Material:Zinc alloycolour:Photo ColorPackage Contents:200 x Hex socket (M4 x 8)200 x Hex socket (M4 x 10)150 x Hex socket (M5 x 10)75 x Hex socket (M6 x 10)100 x Hex socket (M6 x 15)100 x Hex socket (M8 x 20)Only the above package content, other products are not included.Note: 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 +/- 1-3cm.