I have not seen the Quad Gear cab, except on the ATV style four wheelers. The price is sure right! The deal with the ones I have seen on the ATV was that the windshield was hot sealed to the plastic material of the cab and required a top shop to sew on a flap and make a velcro arrangement to remove the windshield to replace it with a marine material plastic substitute every year when it turns gray and you can no longer see through it. No big deal, just something to think about if the one for the Mule is the same way.
There is a slit and flap arrangement on mine, it just slides sort of over the snorkel so it is exposed to the outside air. Since it was second hand, I really do not know if the other guy did that or if Kaw thought ahead.
Kawasaki makes a soft plastic windshield for the soft cab, but I would avoid all plastics and go to an automotive glass shop and get a tempered glass cut to fit the front roll cage. I intend to set my glass about ten inches above the hood, and all the way to the top. Believe it or not, chain link fence panel brackets work great to hold the glass to the roll bar, but require rubber insulators to keep the bolt and hole in the glass from colliding and breaking the glass. Then I will use a boat fabric chunk to fit below the windshield and above the hood, and velcro to hold it to the windshield and to the roll cage. Then just let it snap on the hood with velcro tabs to keep it secure. I tried one of those high dollar glass windshields that fit the full opening and have the gas struts, but at zero the gas struts conk out and it is like pulling teeth to get the windshield open to get the hood open to reach my spotting scope and extra supplies. I did the same thing for my last Polaris after trying to use their goofy OEM glass windshield too.
You will notice I like velcro, when it is sleeting and ice is building up the velcro still works while zippers and snaps freeze solid. I also carry a few bungies just in case.