M6 X 1.00 X 15MM Rubber Well Nut BY DRESS UP BOLTS

Well nuts give you the freedom and protection to secure pieces in hard to reach places that prevent you from using a normal nut. You just have to place the well nut through the opening and screw your M6 bolt-in causing it to compress and tighten.
 
IMPORTANT:
Well Nut requires a 13mm hole.
Torque Specs: 10 lb-IN