Here's the info on the Circuit. It's in new condition, no snags or tears, I only used it about 6 nights, carrying about 12 lbs in great comfort. I'm selling it due to illness related issues (pneumonia has forced me to take a year off physical activity while I recover).
Weight: 32 oz, 3,750 cu inches/ 60 liter volume total
Main body: 2400 (40l)
Front Mesh pocket: 350
Side Mesh Pockets: 400
Extension collar: 500
Hipbelt pockets: 100
Fully padded backpanel, dyneema cross-rip gridstop, elasticized bellowed front mesh pocket.
Internal Suspension hoop, contoured shoulder straps, drawstring extension collar.
All these specs are from the ULA webpage for the 2008 Circuit.
If you like, I can post some photos.