●The package includes 100 pieces of 4040 series M8 ball elastic T-nuts. ●Made from quality carbon steel, these T slot nuts have high hardness and long service, surface is nickel-plated for good rust resistance and better performance. ●These nuts are used for T-slot 4040 series aluminum profile. fit for aluminum profiles with specific slot. ●They are rotatable slot nut with guide plate and balls, easy to roll into the T-slot of the aluminum profile. ●Aluminum profile T-nuts are widely used in construction industry aluminum frame structures, 3D printers, CNC milling machines and robot projects.