Frame size is a mystery to me.. can find nothing mentioning that.. unless, the frame size matches the wheel size... it is Walmart so, yeah, you know how that goes. The only info I can really find is that it is referred to as a "26" Mens Granite Peak"
I sat on it and rode it in store a bit and it was as comfortable than half the MTBs I have tried and more comfortable than the other half (fit wise). The seat will have to go though lol