Stalla IPhone Flash Cards??

Anyone have any experience with these? Expensive for an electronic product… but are they of high quality? I’m thinking of studying with the flash cards until Jan 1st to build a framework for the higher level concepts, and only then open the full texts. What do you think?

its probably just their regular flast card product on the iphone. have you seen the regular flash cards they hit an LOS on the front with an explanation on the back or are formula driven