Mulch plugs allow you to stop the grass from discharging out of the side chute, keeping the grass under the deck to get mulched up into very tiny pieces that fall back down into the grass to decompose and provide nutrients for the lawn. I just got mine and it has been very handy for mowing in tight spaces like this where I wouldn't be able to discharge the grass in either direction due to the planters. It mulches so well, it looks like it's bagged! #Amazing #satisfying #asmr #lawncare #lawn | So