According to our plumber, the hardware needed to attach the seat to the toilet may have been taped to the inside of the box, in which case we accidently threw it away with the box before he came to install it. It may be that there was no hardware included. I contacted TOTO, but the parts are not available at this time. Fortunately, we have the toilet seat from the old toilet. Hopefully, the parts will be available by the end of this month. A disappointment. Why would they tape the hardware to the inside of a box where no one would see it?