I have a Blade Runner, which is a fancy Sidewinder.
It collapses to 29 x 14 x 8 with the motor off.
It differs from the Sidewinder by having the extension as standard, a lower wheel to help guide it in place, instead of having to hold it up by yourself, and hooks to capture the axle. However, mine has two spring loaded tubes that go into the axle, which looks like a better clamping arrangement than the standard Sidewinder hookup.
The Blade Runner retails for $2650, but I'll sell mine for $1600 plus shipping. That includes a battery and charger. Best of all, it's available immediately, unlike new Sidewinders and Blade Runners, which have an unknown wait time, according to the Red Line Aviation site.
https://redlineaviation.com/by-product/
I can't attach pictures for some reason. I'll try later.