[Vistacruise]

The Seller list this as a Giant Boulder. It has 26 inch rims, front shocks, front disc brake, aluminum 3 piece with a Euro bottom bracket, 4130 chromoly steel. He said the top tube was 20 inch. Idk what size that would make this.

I can't find this exact bike on Giants Archive.

 

[mayonays]

Appears to be a 2011 with some parts swapped out? Or perhaps just painted red?

 

[Vistacruise]

The seller just responded that the bike is all stock, The forks are Suntour Xcm V3 ds mlo

 

[mayonays]

They swapped out the fork and wheel to add disc brakes, those didn't come stock on that bike.
Here's the geometry chart on Giant's site, as well as full specs. Perhaps he meant 20" seat tube which puts it at a large.