Read the mothership reviews, especially the not-so-positive. Consider that your dental curve/shape may be different from a product intended for general population.
Thanks! I almost bought this, because it does look like a low price. But yeah, most likely it will not fit my mouth. I have a very big mouth.
I 100% agree these are a bad idea. I understand from two of dentists I know personally, these are on par with not brushing at all.