Frustrated that everyone claims to be “the lightest” without publishing actual weights, I purchased several of the main sprocket options for the 701/690 in the popular 42 tooth size and weighed them myself.
Album with pictures of all sprockets on the same scale, one at a time: https://photos.app.goo.gl/iHMERvZZ511rg1Q68
(Note that the scale was zeroed each time. In the photos with a paper towel under the sprocket it was zeroed with the paper towel on and no sprocket, then the sprocket was added in order to tare the weight of the paper towel. All shown readings are the weight of the sprocket alone.)
The SuperSprox hybrid sprocket is shockingly heavy and in no way worth the significant cost.
The OEM KTM 42t steel sprocket weighs less than the SuperSprox at about 2/3rds of the cost. However, the original 40t sprocket is much lighter. Adding two teeth (5%) adds 30% to the weight!
An all-aluminum sprocket is cheap and weighs half what the other options do, but this isn’t really an option for anyone who racks up a reasonable number of miles. And it only saves half a pound.
If you aren’t cost sensitive the Dirt Tricks sprocket may be your best bet. It isn’t lighter than stock, but it at least lets you move to 42t gearing without gaining weight or losing durability. Otherwise the KTM OEM sprocket is a good way to go. It’s also black, which is nice.
I went with the Dirt Tricks sprocket, myself. Though I’m still tempted to try the all-aluminum sprocket and see how long it lasts.