Delicate, concise and safe, an optimal balance of performance and price, contracted but not simple; Sidewall compressed O-ring helps the box easily reach IP67; The perfect combination of D2PARK circuit packaging and copper heat dissipation technology motivate the whole appliance; The one-way breathable film technology balances the inside and outside temperature and pressure. Safe connection and solar panel protection are its primary responsibility. Approved by TUV and UL, and universally accepted. QC Solar, innovation everywhere!