Tensun via Amazon offers its Tensun International Travel Plug Adapter with 4 USB Charging Ports in Black or Blue for $17.99. Coupon code "TWS2ED94" drops it to $12.99. Plus, Prime members receive free shipping. That's the lowest price we could find by $12, although we saw it for a buck less in June. It features four built-in plug standards (US/EU/AU/UK), four USB charging ports (two with smart charging), and a slide-out plug release button.