The X-Blade Dual Mulching Blade Adapter Kits were designed to turn your ordinary side discharge commercial mower into an extreme grass pulverizing machine. The X-Blade Dual Mulching Blade Adapter Kit in this listing comes with zinc coated adapters, bolts and spacers required for the 900 Series John Deere commercial mowers. The X-Blade Dual Mulching Blade Adapter holds your original blade and an additional mulching blade at a perfect 90 degree angle. Your original blade (lower) will give the clean height of cut and the mulching blade above, with multiple cutting edges, pulverizes the cut grass as it cycles through the deck chamber dramatically reducing grass clipping size. With the use of the X-Blade Dual Mulching Blade Adapter Kit you can not only mulch but bag more efficiently as well. This kit allows you to bag the grass with more vacuum and grass packing than ever before, as well as side discharge with confidence. Also, when using The X-Blade Dual Mulching Blade Adapter Kit, you are ensuring a perfect balance to the machines blade spindles, which will not allow blade slippage, which can cause a blade to over torque and become nearly impossible to remove. We do recommend lowering the RPM’s when you engage and disengage the PTO clutch.