Needle feed machines come in a wide variety, it is more of a feature than a specific machine, for example you can have a cylinder arm needle feed a lockstitch needle feed etc. They are great if you don't want to take the full step up to a walking foot but need something heavier duty than a lockstitch.Needle feed machines will allow you to sew both thin and thicker fabrics for example silks up to leather, they are probably the most popular choice of machine due to its versatility.