Considering the charging security and on the go necessarily. The output of POWER CUBE X adopts1A/5V, 5W. The 7.5w fast charge only 30min faster compared to 5w charging but with much hotter. The 5w design is a comprehensive consideration after contrasting the charging efficiency VS capacity of battery and Charging Security VS Charging speed. While that doesn’t mean we don’t have 7.5w solution in the future.