The 3D-XL converter allows 720p output of 1080p 3D Blu-rays.
There's nothing wrong with going 720p, especially if you're one of those that shelled out for a nice projector before 1080p really kicked in. If you're primarily playing videogames and watching television, the resolution difference doesn't even matter for most content.
But 3D is a different story. If you're hoping to enjoy 3D Blu-rays on your 720p projector, you'll be in for disappointment unless you pick up the new 3D-XL converter from Optoma.
The 3D-XL takes that HDMI 1.4 1080p signal from your Blu-ray player and converts it into a HDMI 1.3 720p signal that your projector can understand. You'll still need a projector that does 120Hz of course, but as long as you've got that – and the appropriate 3D accessories like glasses and a transmitter – you'll be ready to go.
Source: AV Rev