Michael, I have used the ER tools on Diamondmax 9 80Gb (Single platter). I don't remember if it was the WD or Seagate tool, one fit better than the other. I used it upside down so the rounded tip was still near the heads. It is a little loose so extra care must be taken so it doesn't fall out. You also have to be sure it slips under the bottom head or you'll drag it. I have probably used them on the single platter Diamondmax 9 a dozen times. If you have 2 or more platters, upside down won't work. The fat side of the ER tool will be down and won't fit under the lower platter. It shouldn't matter much if the round edge of the ER tool is not near the head, but the fit is poor for multi platter. It will be difficult to get the tool under all 4 heads. That's my experience. That said, these tools work great for the intended drives.