I have similar questions. I was confused, and my local Woodcraft was also confused (although the Festool people were not available at the time).
First they had sold me a backing plate for another sander-it had a hub screw instead of the twist-on fitting, so I was hopelessly confused, and didn't even know I had the wrong one. Doh on me; doh on them . .
Next when we looked at the 493914 in the 2007 catalog (page 90), it is described as 6" diameter (145 mm; 9 hole). However, the part in the store, under this #, is NOT 6"in diameter, it is 5", suggesting to me (standing there at the counter) that it (again) is not the right part for my Rotex 150. Also, it has NO HOLES. (Actually, it has 2 small holes that don't go all the way through, and have nothing to do with dust collection.) The part was green, as shown in the catalog.
We finally decided it (probably?) is the right part -- We guessed that it was a smaller diameter so the 6" felt pads overlap 1/2" on each side. As a result, you have a flexible edge that allows you to buff out corners and rounded edges. (Keep in mind; I'm GUESSING here . . . )
Next issue; (page 90), they show the same part # (488347 for both the soft felt (5 pieces) and the hard felt (5 pieces). The catalog should be corrected to show the hard felt # 488348.
Moving to page 94 (#1), we tried to look at the equivalent part for the RO 125 (#492128), to see what the diameter would be. As luck would have it, they did not provide any dimensions here, and the store didn't have one in stock. Following the logic above, I expect the RO 125 polishing pad to be smaller than 5", but it sure would have been nice to confirm this directly.
Next issue: The FOG moderator suggested recently that we all pay close attention to spelling, so searches will be more effective in the future. Just to clarify this whole mess, Dan -- you referred the pad as # 493194. The correct #, from the catalog, AND from my plastic packaging, is 493914. I believe you either transposed the number, OR you obtained yet another bad # from Festool somewhere. If we have any hope for sorting this out, we need to make sure we're talking about the same thing.
Moving ahead - what do we use them for? I am refurbishing and polishing a fiberglass shower stall, using various Maguiar products. See the excellent thread elsewhere on FOG with lots of details re car detailing (I don't have the link just now). I look forward to applying these techniques to the car as well.
Do NOT mix compounds on the same pad!
Recommendation from elsewhere: Do NOT attempt to clean the felt pads! Allow them to dry in the protection of an un-sealed zip lock bag, then seal them for storage. Do NOT allow them to collect dust, grit, etc. Use a separate pad for each new compound, and label the back of the pad for future reference. (Therefore, you probably want to buy the 5-pack.) To reconstitute later, work new liquid compound into the pad.
Finally, (now I know), do NOT try to wash out the lambs wool polishing pad. The backing stays the same size, but the lambs wool itself shrinks about 25%-30%! [Nice Pad] --->> [Shriveled Garbage]
Please take my word for it; I barely know what I'm talking about here! If anyone has further comments, corrections, suggestions, I'd love to hear them.
Ed Gallaher