I babysit my neice who is 2 and a half and into EVERYTHING!!! The other day she managed to get into my 15 yr old daughter's room, despite the new door knob covers I bought to keep her out of it. While in there she found many Sharpie markers on the floor because my daughter is forever working on projects for school. My neice then proceeded to decorate my daughter's acoustic guitar with her own original artwork!!! Oh My what a day!!! I tried everything to get it off...bleach spray, alcohol, nail polish remover... The worst part was the marker was one of those special ones that writes on black paper and you can still see the ink. I could not get that stuff off. My husband (my daughter's step dad whom she likes to ignore) used a Mr. Clean Magic Eraser and got it ALL off!!! I could not believe it!!! As happy as my daughter was, she would never tell her step dad! But we were all amazed at how effective it was. I bought these a while back and had used them for things like koolaid stains on the counter and so forth. They worked great for that and were easier to use than sprays and stuff like that but nothing has amazed me more than spending 30 minutes using everything under the sun and still having marker that looked brand new on the guitar...then my husband spend 10 minutes and the GUITAR is what looks new! INCREDIBLE! I highly recommend them. They come 2 in a box and I think I paid $1.98 for them a while back so I am not sure what they cost now.