Tacklife USB Power Tester | $7 | Amazon | Promo code HI5QMGI9
Photo: Amazon

Wondering if all those USB chargers you’ve collected actually put out as much power as they claim? This $7 dongle sits between your charger and a phone or tablet, and displays easy-to-read voltage and amperage figures so you can see how much power is really flowing through. Just be sure to use promo code HI5QMGI9 at checkout to save.