Super soft. It doesn't hurt human skin,safe and without any acrimony,the glue is the best cleaning product for various precision digital instruments. | Dust and dirt in gaps or on surfaces will be absorbed by the cleaner. | Reusable, can be used until the color becomes dark black.pack of 4 make sure use for a long time. | Convenient and easy to use, just put the cleaner on your keyboard for a while and remove gently as a whole. | This cleaner may leave small amounts of residue when used on your keyboard. This will not cause any potential issues. A pipe cleaner or cotton bud can be used to remove the residue.