M6-1.0X32 Steel cylinder nut with inside threads , double spring steel leafes , Black and blue zinc finish for anti-rust .
Operation guide for Start Nut
1. Put start nut on the opening of hole and make sure to let Concave side suface the hole .
2. Hit start nut into hole to needed depth.
3. Leaves will be extruded and deformed , which prevent nut was pull-out and slip out .