I purchased this extra-long twin bed frame and boxed spring around 2019, when it seemed my child might be headed toward 6 feet. She slowed down, and now this guy needs a home. I have a mattress, for free, that fits the frame if you would like it. (It was a child's mattress, so yes, it has 1-2 ,very old, stains). You will need, in any case, a mattress that fits it at some point; if you use a regular mattress, the end of the frame sticks out slightly, and you don't notice that until you've whacked your ankle on it.
Frame is approx. 78-79 inches long. Box spring is 5 inches tall. Free mattress is 7 inches tall.