Fred the Red Shirt wrote ...

I have in mind using them on a Sky Pup Ultralight, ...
I'd kinda like to know SOMETHING about what I'm ordering. ...

Azusa makes band brakes, drum brakes & disc brakes. All have been
adapted to a variety of wheels, including the TuffWheels called for on
the Sky Pup. The band brake would be plenty sufficient for taxing &
parking. Brakes for stopping a rollout would be rather pointless on a
Sky Pup given the extremely short distance involved. To see what
you're ordering, check:
http://www.azusaeng.com/brakes/brkmain.html

Daniel