Be careful. I used to love these, but I had one of those ruin a couple of my dress shirts---it's not a super-common problem, but it has been reported by several people.
http://coupondivas.com/product-reviews/purex-3-in-1-laundry-sheets-review/comment-page-2/
For what it's worth, the "fix" in the form letter one gets back after complaining didn't fix either of my shirts, and they both became "yard work" shirts---and I had just bought them within several months of the incident, so I was pretty annoyed.
I don't use these anymore. Now I use the powder that's in the unit, ordering more as needed, and pack a few "regular" dryer sheets instead. I'm thinking about getting an owners' locker for this and other odds and ends so I don't have to think about it for future trips.