MATERIAL AVAILABLE: STEEL, STAINLESS STEEL AND BRASS ADVANTAGES:1.INSTALL SLEEVE NUT TO ACCESS FRONT SIDE OF THE WORK PIECE SCREW IN FROM BACK SIDE.2.INSTALL WITHOUT ANY COMPLICATED TOOL AT ANY LOCATION ON THE ASSEMBLY.3.INSTALL WITHOUT PRODUCING ANY HARMFUL MARK.4.INSTALL INTO VARIES MATERIAL.5.THE FANGS ON THE BODY CUT INTO THE APPLICATION DURING ASSEMBLY.6.EASY, FAST & SAFE INSTALLATION.INSTRUCTIONS OF E-SELF DRIVING NUT:AS THE SLEEVE NUT IS STALLED, THE FANGS ON THE BODY ACTUALLY CUT INTO THE APPLICATION & PROVIDES GRIP STRENGTH. WHEN SCREW ON THE OPPOSITE SIDE HAVE DRIVEN, THE FANGS WILL GRIP APPLICATION TIGHTLY.