I've got the 15mm UFF (Sky Rover branded) and I love it. It's turned out to be a very useful focal length in my various small refractors and it delivers bright, sharp views in a very compact and lightweight package.
It's definitely worth trying out, especially if you can pick one up at a bargain price.
The design is a scaled version of the 18mm and 24mm models.
Thanks, I think it's already a bargain price....