A camera lens has a minimum distance that it will focus to - any closer and you just get a blur. There are lenses that focus much closer, called macro lenses, but these are very expensive and are generally 1 focal length. Even zoom lenses that say they have a macro facility tend to offer it at only one length, normally the telephoto end.
These filters screw onto any lens, including zoom lenses, with a 58mm filter thread and reduce the minimum focal distance of that lens.
They are light and come in a sturdy, though soft, pouch, so you could take them with you - as a just in case - in the knowledge that they won't result in your camera bag feeling like you have added a small elephant. Something that cannot be said for many macro lenses.
Each filter slips into a mesh pocket in the pouch and they come shipped in individual plastic wrappers. I would have preferred these wrappers to have been a soft cloth as they are really just packing material and am not sure of the softness of the mesh. I guess it is unlikely to scratch the filter, but a bit of grit trapped in it could.
The minimum focal distance is reduced most by the +10 and least by the +1 filter. In use I have found that the higher strength filters also appear to reduce the area of focus across the image, though this could be due to the fact that depth of field (how much of a picture is in focus front to back) reduces the closer you get to the subject.
They do not appear to absorb much light so my camera settings were pretty constant whether I used the +1 or +10 filter. I couldn't detect anything in the way of distortion either, which was a nice surprise.
Given that you can buy one close-up filter for the price of these 4 the price is impressive.
Recommended for anyone who does not have, or does not want to buy a macro lens, but takes the occasional close-up of flowers, insects etc.
4 rather than 5 stars as the pouch, while made of ballistic material (no me neither) is soft, so a monopod or other hard object in a hastily packed bag could break a filter, and I am not sure about the mesh pockets.