First Frets Violin 1/4

This aid is a very good tool for beginner students. My seven year old found it much easier than using stickers. The lines are more accurate and they are visible for each string.
No real cons except it can be a bit awkward to apply, but once on correctly, it does not move.
My son had one a few years ago and it stayed in place for the few years that it was in use. Excellent product.