It holds about 5 recharges for most modern Android flagships, or 10 for the iPhone 7/8, and can top off your iPad Air battery twice as well, or, needless to say, your Mac, as it has the same output rating as the laptop's own USB-C charger.
Those Type-C USB-PD portable chargers are rare and expensive still, as they can be charged thrice faster than regular banks, and the output is strong as well, so the RAVPower 26800 PD Portable Charger has an $81.99 price tag that hasn't budged since its introduction, but Amazon's Primed Day deals countdown now lets you have it for $53 plus free shipping by applying promo code Q489VTDR at checkout.