Yes, you can say I was excited. Why? Here is the dilemma, you are painting but you are not finished yet. Two choices for the care of the paint roller, one wash it, two put it in a plastic bag until tomorrow. The first choice is mediocre since the roller will not dry overnight completely, and if it finally dries it is stiff and does not hold the paint well. The second choice is good for several days, however, it is messy, it gets lost among the other bags with stuff.
I used the latter successfully on several jobs with the thought in the back of my mind that there has to be a better way.
There is the paint roller cover, keeps it sealed in plastic, does not dry out or worst gets stuck on the roll holder. Anyway, at $5.98 a piece it is not a cheap alternative to the plastic bag but a more durable and cleaner one.