Size and Type: It measures .203 x .386 x .630 inches long with 1/4-20 thread. Fit for 1010 series and any other 1.0" based aluminum extrusions. T-Slot: 6mm. Material: The ball spring T-nut is made of 1045 steel with zinc finish. Durable and rust-proof. Quantity: You will have 20pcs 1/4-20 spring T-nut. Install: Roll in T-nut with Ball Spring can be inserted into T-slot easily. To attach joining plates, corner brackets, and other t track accessories to aluminum extrusion. Widely use: This T-Nuts widely used for building industrial aluminum frame structures, 3D printers, CNC Routers, CNC laser cutters, Robotics Projects, 3D carvers, etc. Quantity: 20pcs. 1010 Series or 1.0'' based aluminum extrusions profiles with 6mm T-Slot.