It's actually both...it's made from PVC pipe modeled after the structure in Square Foot Garden...we added with zip ties an additional pipe underneath- far end has end cap, 2 pop-up sprinklers facing down and a quick connect on end nearest. So hoop structure can be used for early or late planting and the addtional pipe can be for quick hassle free watering during the summer. Not the prettiest but very functional.

Theres a youtube channel called growing your greens that he added a removable extension to the top to allow trellising of melons and cukes.

What a wonderful garden! Looks like an inviting place to work, and sounds like it works hard itself, too!

Looks great but usually watering vegetables from the top like that causes a lot of blight and bacterial disease. Dropping them down so the water goes to the soil, where the plants take it up anyway, seems to be a better choice.