RulerPower

USB-C cables tend to wander between phones, tablets and laptops, which is how they end up plugged in at home when a phone runs low elsewhere. RulerPower addresses that by integrating a 70cm retractable USB-C cable into the body, alongside a separate USB-C port. The maker says both outputs support up to 40W, allowing two devices to fast-charge at the same time.

A cable that works both ways

The built-in cable also recharges the battery itself. Pull it out, connect it to a compatible adapter (sold separately) and, according to the maker, RulerPower accepts up to 40W input, refilling its 10000mAh cell in about 1.2 hours. The retraction mechanism uses a small, durable rotating bearing: the cable locks at whatever length is drawn and rewinds automatically with another short tug. The cable itself has a TPE outer layer, braided-shield tinned wire and a core of 12 bundles totalling 144 high-purity copper strands, each 0.06mm in diameter; the maker compares its quality to Apple's braided cables.

Silicon-carbon inside

The compact size comes from a silicon-carbon anode battery, sourced through a partnership with a supplier of EV-grade battery cells, the maker says. Combining a porous carbon structure, nano-silicon deposition and silicon blended into graphite, the company claims a 16% gain in anode energy density over conventional graphite and an overall energy density of 740Wh/L. Compared with conventional ternary lithium polymer cells, it cites roughly 40% or more less heat and a body on average 35% or more smaller for the same capacity, resulting in dimensions of about 65x65x36mm.

• Capacity: 10000mAh; weight: 176g; size: approx. 65x65x36mm
• Outputs: 70cm retractable USB-C cable plus one USB-C port, up to 40W each
• Input: up to 40W via the built-in cable; full charge in about 1.2 hours with a compatible adapter
• Protocols: Quick Charge 4+, PowerDelivery 3.0 and proprietary phone-maker standards, per the maker
• Protection IC against overcharge, over-discharge and short circuits
• Colours: White Jasper, Grey Blue, Black Onyx

Finish and compatibility

The shell follows what the maker calls G3 continuous design for smooth, uninterrupted curves, and is formed in one piece using moulds it says match the precision of those used for AirPods Pro, finished with a double pearl coat. The maker states that RulerPower automatically matches output to the connected device and can charge everything from earbuds and phones to tablets and thin laptops.