Premium Aluminum Grass Catchers from Accelerator. This extension will increase the standard catcher size to 7.5 cubic feet.  Light weight and durable.
For use with the Accelerator 4.15 Cu ft Catchers

Note: The extension is best used when collecting leaves and should not be used for grass collection. Heavy grass can throw the mower off balance and create uneven cutting and undue stress on the machine. 

Verify this catcher will fit your mower with the Accelerator Fit Guide. (Link opens new window)