This means it’s not only the fastest way to charge devices that can support a higher charging rate, but it is enough to charge USB-C devices such as your USB-C laptop that won’t charge over a standard USB adaptor. Also see: Best power banks and Best USB PD power banks The ‘up to 100W’ is important: this Anker power bank offers 22.5W, which means it will charge your USB-C laptop only if it meets that requirement. The 12in MacBook (which ships with a 29W adaptor) apparently does, though our Mi Notebook Pro does not. You’ll need to carefully check the spec of your laptop, or perhaps the adaptor you’re currently using to see if it will be supported. The Anker PowerCore Speed offers 20000mAh of power for keeping your devices going, and as such is a lower-capacity and cheaper alternative to the 27W  26800 PD we reviewed last summer. But in design – and, of course, capacity – it looks more like the Anker PowerCore 20000, a slightly cheaper device but one with two USB-A ports and no support for USB Power Delivery.  You’ll pay £49.99 for this Anker PowerCore Speed 20000 PD in the UK, or $79.99 in the US. Although our review sample shipped with a 30W USB-C PD mains adaptor (with US two-pin plug), we don’t believe it comes with one in the UK. This should explain the difference in price, since you’ll pay upwards of £20 for such a plug in the UK.  Even so, a penny short of £50 for a device that offers insanely fast charging – and recharging (in just four hours), with USB-C PD also supported on the input – and up to 20,000mAh of power for your mobile devices sounds like good value to us. There’s also peace of mind associated with buying from Anker, which is one of the best-known brands in the power bank market. Of course you won’t actually see 20,000mAh in real terms. Power banks typically operate at between 60- and 70 percent efficiency, so you might get around 13000mAh for charging your devices. That’s still enough to charge an iPhone six times or Galaxy S8 between four and five times. The design is Anker’s usual fare, a rectangular plastic brick with a matte finish and softly rounded corners. Four LEDs are used to show how much capacity remains, which doesn’t give an especially precise impression when each LED represents 5000mAh. The power bank is pretty heavy at 371g, which is understandable given the capacity, but it’s elongated design makes it feel bulkier than it is. You’ll find it more practical carrying the Anker in a bag than a pocket. On the side is a button that activates these LEDs to show you what there is at a glance, though charging is automatic when you connect your device. You can add two if you like, with two ports found at one end: one is a USB-C PD port, and the other a 10W USB-A output with PowerIQ (tech that identifies your device type and delivers the optimum amount of power). You can’t charge a device a recharge the Anker power bank at once (known as passthrough charging), though the USB-C PD input means having to charge each device separately is less of a hassle. Marie is Editor in Chief of Tech Advisor and Macworld. A Journalism graduate from the London College of Printing, she’s worked in tech media for more than 17 years, managing our English language, French and Spanish consumer editorial teams and leading on content strategy through Foundry’s transition from print, to digital, to online - and beyond.