This is a 26" frame but it's a rather small frame for a 26" bike.. the bike was originally. One of those roadmaster mountainbikes they sell at walmart, the front fork actually costed more than the bike it's self but the ride quality and stability is well worth it... totally night and day compared to the original front suspension fork it came with.
Actually it's a Roadmaster Granite Peak but I'm sure it's the same frame as the Huffy Stone Mountain and a few others. .. for a cheap bike it has really nice welds on the frame and the frame is nice rigid and strong too.