These sensor swabs are designed for cleaning the sensors of full frame digital SLR's - type 1 denotes the swab size. You must use the right size swab for your camera's sensor as they are designed to reach all the way from the top to the bottom of your sensor, enabling you to simply sweep them from side to side to cover the whole area of the sensor and clean the camera.
Each box contains 12 swabs, although they can also be purchased individually as each swab is self contained in a plastic package (quite wasteful from an environmental perspective, but when cleanliness is the objective here, it is a necessity).
The swabs themselves almost look homemafe - essentially they consist of a plastic stick and a bit of material folded flat over the end with a tiny rubber band holding it all in place. That said, with this sort of item it is not how it looks that is important - it's how well it works.
It is important to note that you don't use sensor cleaning swabs in a dry state - you need to add 1 or 2 drops of sensor cleaning fluid to the end of the swab to make it damp, but not saturated. You then sweep the swab from side to side across the sensor of your camera, applying a small amount of pressure (making sure you don't press too hard and damaging your camera in the process).
It can take a couple of sweeps to remove all marks on the sensor and the swab won't be capable of removing any stubborn marks. It is also good to note that recontamination is likely - especially when you consider that in order to clean the sensor you have to have it locked up in an exposed position, with the camera pointing straight up, which are ripe conditions for sensor contamination. When you think you've got the sensor clean it's a good idea to put a lens back on and take a photo of the sky, then zoom in on it - if there are any marks left, you should be able to see them now.
Recontamination is a problem and a risk, regardless of the type of sensor cleaning you employ and as such is not a specific fault of this swab. However these swabs can on occassion shed fibres of their own and thus actually add to the problem - I would say this happens roughly 1 time out of every 10.
Essentially a sensor swab system is the most effective way of cleaning your camera's sensor, it is also the least likely to damage your camera as long as you know what you are doing. If you don't know what you're doing then I would recommend you leave it to a professional as they will repair or replace your camera if they damage it in the course of cleaning it. If you do decide to do it for yourself my two top tips are: 1) Don't apply too much pressure and 2) Make sure the battery is fully charged before you attempt to clean - if it isn't and the battery dies whilst you're cleaning it, the mirror can snap down on the swab and you'll break your camera.
Price wise these cost about £36 for a box or £4 each.
We do sensor cleaning where I work and this is the product that we currently use for sensor cleaning and they have served us well over the years - however we are now running down the last of our stock and switching over to sensor swabs made by 'visible dust' as these are the same sort of item but aren't prone to shedding their own fibres.