If you have never had to fit a new set of strings onto a double bass then you will have trouble appreciating the benefit of this particular accessory. It is however, one of those things, that when its needed, you need it a lot! ... a double-bass string fit-out can take quite some time. This is not only due to the overall length of the strings, but also due to the fact that strings (again, due to their length), stretch quite an amount when you start tensioning them up over the length of the instrument. The net effect of both of these things is that without a string winder you can end up giving yourself quite an amount of wrist sprain while re-stringing your instrument. This particular item is light and small, so will hide away in your case easily, but is also robust enough to last a long time. It is important when purchasing a DB string winder to ensure it is specifically designed for a Double-bass and has a good side socket for the metal end of the BIG DOUBLE BASS machine-head to fit into! ... all in all, very glad I purchased this product.