nut 27 mm? I just installed it two days ago. Not having the usual dust cover, they look a bit odd - there's bare metal in the gap. At first I thought it wasn't fully seated even though I tightened the castle nut to spec. Let's get back to the 27mm nut. I didn't have such a big outlet. I didn't know it needed such a big one. I was lucky to have another car and cargo port nearby so I could pick it up. I want you to emphasize that fact. In any case, they make a high-quality impression. I had a Zerk fitting that didn't leak grease until I could free the tiny ball bearing. That's the only problem. They fit perfectly.