I have a lot of laptop accessories, bags etc and was looking to slim down my collection for traveling abroad. I wanted a sleeve that could protect my 15" MacBook Pro and carry the power supply and fit inside a small carry on trolley case for the plane.
In simple terms this was the perfect sleeve for the job. It is well made with a durable zip for the main pocket and then there is an extra pocket on one side (the reason I bought my one) to hold all manor of items. Whilst it is probably designed to carry small light weight items like a USB mouse, phone, CD's or notebook & pen etc I find that it does a grand job of holding my power supply as well (I make sure that the laptop screen is on the other side of the sleeve should there be any pressure from the power supply whilst in my suitcase).
All in all it is a simple but very affective sleeve. Buy one, you won't regret it.