You might want one, or even two, to hold the first half of a concert program in one, and have the second half music in your second adaptor...ready to quickly swap in at intermission, so you can spend the time chatting about the performance instead of fussing with paper during your break.

And why carry twice the weight of music through a concert if you have an intermission?

It attaches using the cords that are already in your folder. There's a video demonstration below.  People who sing in more than one choir can also use a second adaptor keep music separate. Attaching the adaptor to the folder with the cords adds security, but is not essential, as music couldn't slide out past the bottom strap. You can just drop an adaptor with your set of music into your folder, and be ready to go.

As these ship by weight, you might find that more than half a dozen are still the same minimum quoted shipping cost - feel free to edit quantities in the shopping cart for best total value, and gift a few to friends in your section.