Ribbed nutserts are essentially a blind rivet with internal threads , great for adding an anchor point for fasteners in material that can only be accessed on one side. Rivet nuts are pulled with a thread setting tool, similar to a rivet gun. The low profile head allows for a near flush installation while giving it sufficient bearing surface area. Grip range is the amount of material the nutsert will be going through, not the actual length of the nutsert, which will always be longer than the grip range.