The quality of this greenhouse is decent and appropriate to the price. ie. It isn't super quality and not very sturdy, but is good enough for the purpose. Very simple to put together, no tools required. It holds 2 standard seed trays side by side on each shelf. They hang over but you can still zip the cover closed. The castors are a good add-on feature, but I’d be wary of moving it too often give the level of sturdiness of the frame, especially if fully loaded. It appears larger in the photos on the website than it is in reality, but the specifications measurements are accurate. Overall it’s a good product and will do the job.