Q.Can I use it with an extension cord or power strip？

No, it cannot be used.

It may cause fire, electric shock, or abnormal heating or deformation of the power plug. Even if there are two or more outlets in an indoor wall outlet, please use them independently. Electric heaters have a large power consumption of 1200W-300W. Extension cords and power strip will cause excessive loads on each part beyond the allowable amount, making it impossible to use the product safely.