I think ours is swivel straight maybe? Anyway we purchased it at a True Value hardware store. I know if was $30ish about 8 years ago. Totally worth it. Ours works this way: there is a large cup that goes over the base of the tree, it is probably 6 inches deep so make sure to leave room on the trunk when you cut it or check that when you buy the tree. The cup does screw in but you don't have to make it perfect. The cup sits in the base of the stand and you use your foot to press a lever on the stand, swivel the tree straight, release lever and voila, straight standing tree. We fill our tree with an empty wine bottle

(the long neck is easier than a pitcher)

. I know the stand when filling holds not quite three bottle worth of water.
The base is bigger than typical but it works so well to me it is worth it. we have had some pretty crooked trees stand straight thanks to this