Yea, what Pnoy said... it is GT-Factory.
First of all... it's not a reason to charge more money, because the kit is actually $999 (tunerracing.com) vs. an average of $1400 for regular VDC kits out there.
Second... it is stronger because two struts are better than one & will help lift the door with more ease than with one.
Third... these are more or less universal struts. So if one happens to go, you can at least pick one up at I think it was a auto or hardware store (forgot where, exactly) for around $15.00 to $20.00. If one of your struts happens to go on most of the other kits out there... it's like a $150 replacement (est).
Fourth & Finally... it's not that hard to close the door at all. It will close with just one finger & very little pressure.
They do go vertical or near-vertical, depending on where you set it, but it will stay up at any length without wanting to go higher or fall down.