For general conditioning:
Lightweight, compact and easy to set-up, you can take them anywhere.
Straps are 14.5ft in length.
A better value, I think, are the Elite Rings for $72.
UPDATE:
The best deal of all right now is from Coach Sommer:
Normally retailing for $72, The Xtreme Rings are currently on sale for $55.
Consider these NEW support resources, as well: a Rings book and 5 DVDs from Gymnastic Bodies:
Gymnastics Coaching.com 