In reply to David Coley:
The 'specific instructions', (their term, not mine) does specify for single ropes 8,6 mm, is the opera not 8.5?. Are they dry treated and new by any chance. Also check instruction 4.2 re single ropes. Even so, you have to hold the break strand
It's difficult to read these things on a full screen, but it is worth it, I have even printed them out and taken them to a wall.
It's one of the few bits of gear where I read the instructions and more than once. The other is the Petzl Connect.
If you're new to the device or relatively inexperienced, I would suggest non pressurised situation practice, particularly abseiling. Get it right it's the safest device I know, you can probably tell I'm a believer in this device.