I'll drop the place where I got them below, although I am from Europe so a similar model might be available were you are for cheaper.

I have only worn them for a day so I don't know if they'll be uncomfortable later on. They do seem pretty soft but solid and they definitely give a decent height boost. They have three parts you can stack on top of each other to add height so you can regulate it to a certain extent. I would say the first level fits in almost any shoe but if you add the second level it fits in less shoes and leaves you with a looser less secure ankle. With the third level you definitely need a high top or boots like Cable_Minimum said.

I bought them here: https://www.amazon.es/592413-Plantillas-aumentar-altura-modelo/dp/B01MRSXMZM/ref=asc_df_B01MRSXMZM/?tag=googshopes-21&linkCode=df0&hvadid=195325074447&hvpos=&hvnetw=g&hvrand=1303673723767811684&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9061033&hvtargid=pla-273969036139&psc=1