You can order new velcro for free. Just logon to your account or call the tollfree number. Evidently, use of sun shades will cause heat to build up and the adhesive fails.
POS,
You can have up to three tags on one account. They're free. Get one for each of your most commonly driven vehicles. If you need to switch the tag to another vehicle, just notify NTTA before hand.
I'm a big fan of toll tags. I don't use the tollway often but it is nice to have when I do.
They're free (with an initial $40 balance and credit card on file), the tolls are cheaper and it's a whole heck of a lot faster. You can also use them at DFW Airport.
Our toll tags are behind the rear view mirror in both our cars.