ITEM NAME:50x Thread Tee Nut Spring for 30/40 Series Standard Extrusion Slot M4-M8 M5 img *{margin:0;padding:0;.Size: M4 M5 M6 M8. For 30/40 Series Standard Aluminum Profile Extrusion Slot. 50pc T Nut. T-nut can securely fix other connecting parts on the profile groove. During assembly, it can be automatically positioned and automatically locked.