Tensun via Amazon offers its Tensun International Travel Plug Adapter with 4 USB Charging Ports in Black for $17.99. Coupon code "XRRX7UJC" drops it to $12.99. Plus, Prime members receive free shipping. That's tied with last month's mention and is the lowest price we could find by $12. 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.