I ordered a Sharp Model R559YW, but received Model R-551ZS. They both seem to be about the same, not much if any difference. FedEx left the box on the porch. The box was partly open and had a couple of holes in it, which indicated it had been roughly handled during shipping. A small piece of something which appears to be the inside tip of one of the legs was loose in the bottom of the oven. It doesn't seem to adversely affect operation of the oven, so I'm trying to use the oven.
It seems to have a lot of sensors and can heat up items with merely the touch of one button. I can also heat litems by touching buttons for the number of seconds I want to heat it. If that's too long a time, the oven will turn itself off completely and after a while, it will re-set itself. However, then I have to reset the clock to the correct time. So far, I feel pretty pleased with the oven.