String Savers?

Hi guys i saw that federer and many other pros are using string savers what are the pros of these and the cons they are quite expensive imo so please could you tell me before i spend money


I use them in the summer, when I have a gut/poly hybrid.
I put them in the exact position as Fed.
The gut doubles its life. That's it.
I can't see any other advantage. No extra spin, nothing.


Hall of Fame
I always use them with natural gut since it's so expensive now. Gut lasts longer, but remember they do tighten up the string bed a bit. The babolat ones work the best.


I quickly grew tired of using them. I put them in, hit a few balls, and the string savers fly off. Not worth the expense to have strings last a little longer.