Long and short: They work fine but are inferior products. I have purchased some.
First thing I noticed was the reflectors are not shaped nearly as well... the curve is different, and the spike between bulbs is shorter and a different angle. (compared to a hydrofarm side by side.)
The next thing I noticed was that the bulb-connectors are stupid "slide on" floating attachments that hang loosely at the ends of the fixture from wires. There are also clips that hold the bulb directly on the glass to keep it from moving. These are a bit annoying to connect and disconnect, especially if you are trying to get at them from around plants to do a bulb switch between veg and flower. Contrast this against a hydrofarm fixture with nice self-holding bulb connectors that you just rotate 90 degrees to engage/disengange and slide out.
The third thing is, the ballast quality will be lesser more than likely. This is not as critical as it probably just means shorter shelf life, and the inability to extend the leads if you want to remote the ballasts in the future. HOWEVER... ONE of my ballasts in the fixture buzzes when turned on. It still works, but the noise was a little disappointing at first.
Food for thought... investigate closely.
