I don't know long term but they operated in two walkie talkies consistently over two days and were still operating when my grandchildren left to go home.
It should work on any iPad Pro EXCEPT the 2018 version, the one without a home button. That needs USB-C to charge, the same connector as the new MacBook Pros. So if you're looking for a charging cable for an iPad pro, if your iPad has a home button this should work. If your iPad has no home button and the screen has rounded corners, you need USB-C.
The item ships in 2-3 business days and takes another 3 days or less to get to your home!
If you wish to know how far away from your phone or iPad they will work I can give you an idea based upon my use? It depends upon the environment. In my home with walls etc. it works easily 30 to 40 feet. If you have brick, stone or metal around it will be lessened. If it is in an open area, clear line of sight it would be farther.