@variablepulserate I think this is the one, https://www.amazon.co.uk/ELECJET-PowerPie-20000mAh-Portable-Compatible/dp/B081S471NN/ref=sr_1_1 - the entry in the Amazon Oz store is different but the device looks identical.
It contains two batteries of 3.7v @20,000 mAh but the actual output is 13,500 mAh.