This is the cheapest this extender has ever been. Normally it's around £370 to £400. For those in the know, this is the only way to extend your focal length cheaply. It doesn't work with all Canon lenses but will work with L's and the shift and tilt lenses. provides a 1.4x magnification with minimal quality loss and sacrifices 1 stop in light.
I own this and use it with a 70-200L and 135L, cracking quality and far cheaper than buying a bigger lens.
I paid a lot more for mine, but never regretted it.