Regarding the "SINGLE SLICE" slot designation, some toasters do come with a "single slice" or "extra-lift" feature, which allows you to toast a single slice of bread in one slot. This is helpful for energy-saving when you don't need to toast multiple slices. In such toasters, only the slot with the bread will heat up, saving energy compared to toasting two slices.
Remember to look for safety features and make sure the toaster you choose is designed with quality materials to ensure safe and efficient operation. Always follow the manufacturer's instructions for proper use and maintenance of the toaster.