The MTD Mulch Kit (Model # OEM-190-116) is designed for 38 inch or 42 inch mower decks that are used in the '600 Series' lawn tractors.  It will fit on lawn tractors manufactured after 1996.  It will not fit mower decks prior made in 1996 or before. 

The parts (components) of the kit (as seen above) include a mower deck plug (mulch plug), two deck skirts that fit a 38 inch deck and two deck skirts for a 42 inch deck.  There is assorted hardware (self-tapping screws, plastic wing nut, carriage screw, etc).  When you puchase the kit - you get both deck skirts - it's sort of a waste of money and product.  But that's the way it comes.  Personally, I bought a mulch kit and then sold the 38" deck skirts on Ebay because I didn't need them.  You should ensure your lawn tractor has mulching blades installed.  Usually, the MTD line does have them installed.  If you bought your lawn tractor used, you may want to check it out. 

The installation instructions are clear and concise.  During installation there is only one issue that may concern an owner.  My mower deck came with pre-drilled holes to attach the mower deck skirts.  If you have an older mower deck, you may have to drill the holes (using a 9/32" drill bit) to attach the mower deck skirts.  The instructions also suggest that you may want to remove the mower deck from the lawn tractor when installing the mower deck skirts.  I used car ramps and drove the lawn tractor up on them.  I found a point between the top of the ramps and the bottom where I could access the mower deck.  During the installation, I used the self-tapping screws to attach the mower deck skirts and I also applied an anti-seize compound to aid in the removal of the screws in the future. 

MTD actually wrote usage instructions in this instruction manual.  Therefore, I will not go into any detail about the usage of the mulch kit.  In a nutshell, don't mulch wet grass and make sure the grass isn't overgrown.

Overall, I use my mulching kit about three or four times in a mowing season.  I normally bag the remainder of the season.  I mulch (cut) the grass after I have applied any fertilizer or weed preventer.  I would hate to apply these products and then just suck them up into the baggers.  I also use the mulch kit after I have aerated the lawn.  I use a plugger type aerator on the lawn soil and again, I would hate to suck up the plugs (that are grass/soil) into the bagger.  I also keep my blades sharp to ensure an effective mowing/mulching/bagging effort. 

The mulch kit is easy to change from a mulcher to a bagger.  You can always leave the deck skirts on the mower deck.  You just remove the mower deck mulch plug (big black thing), and install the bagger chute tube.  It only takes a few minutes to change between the two.  You can also leave the mower deck skirts installed if you just want to mow the lawn and leave the clippings on top.  This is nice when you accidently let the lawn grow too tall and your trying to make up for it.

It's a nice accessory to my lawn tractor and it has worked very well.