Don't know anything about this frameset, other than it's alloy (aluminum) and very nicely welded. Might be by an independent frame-builder. Headset and BB are installed. Also one crank and pedal, which I can remove if desired.
I got it through my old bike shop, and started to build it up years ago for my daughter, when she was going through a BMX phase - hence some of the scratches to the paint. She'd moved on to something else before I finished it, and it's been sitting in the basement ever since - hence the rest of the scratches to the paint. It's never been actually completed and ridden, so "new".