What is inside a Power bank?

Power bank inside: You might have a question that what is inside a power bank. So, this is how it looks inside a power bank. This is a 32000 mAh power bank of a reputed brand sold at rupees 199/- or 3$.                                                 

I observed clay at the bottom to hold chip and battery(not sure what is it called). They were joined by a thin red colored wire.This power bank can charge all mobile brands existing these days, it roughly weighs around 350-400 grams.