Tensun via Amazon offers its Tensun International Travel Plug Adapter with Dual USB Charging Ports in Black for $15.99. Coupon code "HMOA8987" cuts it to $11.95. Plus, Prime members receive free shipping. That's $31 off and tied with our mention from a month ago as the lowest price we could find. It features four built-in plug standards (US/EU/AU/UK), two USB charging ports, and a slide-out plug release button.