I agree with Jacey. Here's an example of some jeans with a tonal band: http://www.alexandermcqueen.com/gb/alexandermcqueen/jeans_cod42637438qw.html As you can see, it's a shiny stripe that's different from the rest of the garment.

WOW! This is a perfect example of the difference between American English and British English. I had never heard of a "tonal band" when it comes to clothing, but apparently it is used in other English speaking countries. I learned something about English today!

The word "tone" can mean a musical quality, like a note, but it can also mean a shade of colour, like "skin tone". A "tonal band" means a stripe of a different colour than the main colour. Think of blue jeans with a black stripe on the leg. You can also find this on jewelry, like a white gold ring with a rose gold tonal band.

It sounds like a word mistake, I can't think of any meaning for "tonal band" when it comes to clothing. It is common for instructions to be translated into English from another language and the translation is not correct. This may be an example of that.