This part serves its intended purpose and replaces one of the two wrenches needed to tighten the collet nut to apply enough force to seat the round shank drill bit properly in the holder to lock . It really needs to be tightened all the way down or the drill bits will tend to rotate in the adapter. This part is necessary as the bit holder shank material is quite soft and does not hold flat surfaces well when unscrewing. My only criticism of this part is that the finish (or lack thereof) is terrible, not even a one off Chinese imitation would make the factory floor look like it. Give it a bead shot or somersault shot or something, this thing looks like you put it on a leash and pump it up behind the Griswold family station wagon for 30 freaking miles. It has craters that would turn the moon red. I would deduct 1.5 stars if I could but I don't want to be mad and go for a full 2 stars as this piece really does the job, it just won't win a beauty pageant as long as it does.