Nice sheets. I've never seen a fitted sheet with an extra strap to help it stay on. That is a great idea, especially on a kid's bed.
The sheets are soft, not too crisp. They are also not rough like a bargain sheet set. Seems like a good sturdy tight thread weave. You get a full set the top and bottom sheets with pillowcase. Perfect for our memory foam twin bed mattress. Our mattress is not over tall so the fitted sheet worked well and would have even without the extra strap - but we have other mattresses that are super thick and the strap would be so vital in that case. Although, kids bouncing on the bed does have a tendency to make fitted sheets fly off in some cases and this set will never have that particular issue.
I have not washed them yet but it seems that the laundering is the same as any other sheet set.