The following picture shows, how to wear that tab. One rubber band goes around your middle finger, the other one goes around your wrist. Change the length of the rubber bands with the string stoppers to adjust it to your prefered measurements.
The last picture can be used as a stencil. Just print it out and transfer the form to a piece of leather. The given sizes are perfect for a (my) medium sized hand. Just scale it up or down to adapt it to your hand size.
That's it for today. I hope you liked it - stay curious!