Even though a lot of people don't use CD's any more, I still burn my music on to the discs so I can have a copy of the original or to have an extra copy in my SUV. If you only have a couple of CD's then chances are you won't need to label them but if you have movies, music and photos stored on discs eventually you are going to need to write on them or at the very least label the case for them. I got the four color pack so that I could label my music CD's as well as the DVD's that I made copies of. These are better to use than regular permanent markers because there's no chance that the ink is going to smear and there's no metal near the tip that could cause scratches on the top of the disc. These should only be used on the top part of the CD or DVD, using them on the reverse side could cause the laser to not be able to read the data stored on the disc. If you buy discs in bulk chances are there won't be a section on the face of the disc to write on; if that is the case then you can use these to write all the information you need to know about the contents of the disc. The pack has four colors; red, blue, green and black. The tip on the marker isn't razor thin but it isn't so thick that you can't write in small spaces on labels. These last a long time but they have caps and you need to recap them when you are done with them or they will dry out. The ink is non-toxic so if you get some on your fingers it won't harm you.