I have it on all my rulers and it works. I just saw a tip that you can use a dab of rubber cement on the back of the rulers to help from slipping, and just rub it to take it off. It might be worth a try (a lot cheaper). Let me know if someone tries it.
I also used the invisigrip to cover my camera screen to prevent scratches, had it on there for a couple of years and works great and is still in place.