This T Type M3/M4/M5 Nut For 20×20 Aluminum Profile is used to assemble the frame along with the corner pieces these slotted nuts are compatible with the standard 2020 aluminum profiles and can be used with standard M5 machine bolts. These nuts are made from high-quality material giving them a longer life. The nuts have a rough edge on one side making them easier to grip on the inner edge of the 2020 aluminum profile.