These are essentially a wrap with a pocket, which is "stuffed" with a booster pad or similar to obtain the necessary level of absorbency.

They are excellent for when baby starts to run off during nappy changes or when "out and about" as they are quick and easy to put on.  Different brands fasten with poppers or velcro.  They can be as quick and easy to put on as a disposable.

As the absorbency part of the nappy is separate to the rest of the nappy, I do find that these dry quite quickly, and can be easily used by those without a tumble dryer (most have a fleecy liner built in which means that any parts of the nappy next to the delicate bottom is soft, regardless of whether they have been line dried or not.