I've been using those on the riding mower and tractor for a couple years now, I'm sold... A lot of times I have one of those insulated 32oz tumblers while mowing (make whatever assumption you want, it's not usually water

) and it works unless I go over just the right bump with a full cup, that one time the cup made it under the tractor and brush hog with just a dent in the side and ovaled the outside so I straightened it, didn't even break the lid somehow... The one on the riding mower since I mow slower with it isn't an issue, the dust lines don't even move...
I agree, they're a good purchase, worth the $12 or at least they were that when I got the two I have...