I can not urge you enough to NOT take them. One in particular has 250% of the daily recommendation for Iodine. If you have any issues with thyroid you can and probably will end up in ER with serious heart problems. They have NO thyroid extract in them, rather they are full of iodine and other vitamins to allegedly help with underlying thyroid issues. They are dangerous and are in the process of being investigated.
I repeat there is NO thyroid hormone in them and they are full of Iodine which in high doses as these are are down right dangerous. It is a money making gimmick by companies jumping on the band wagon of 'natural' medicines.
In the US, over the counter thyroid supplements are not allowed to have any measurable thyroid hormone; as near as we can figure, it's pretty much inert thyroid tissue.
I've only come across this once where I read that it is over the counter (OTC) and thus the potency is pretty low so a person has to take a lot of it in comparison to prescribed medicine. But that is all.
I personally am on the bottom of the range for Free T4 and if my new Dr will do nothing for me because my TSH is in the middle of the range and my FT4 is at the bottom end but still within. I may very well be tempted to give this a try as there is really nothing else to do but continue to look for another Dr.