The Ultra O is a very practical biner that works exceptionally well in pulley systems, big wall environments and DMM considers it to be their perfect aid climbing biner - and some climbers prefer to use an oval for belaying. Its hot forged, I Beam panels maximise the strength to weight balance of the biner.
At some point all of us will need to use a pulley system, most likely in a rescue situation. Oval biners are important because they allow pulleys to sit in a correctly loaded and equalised position. The symmetrical shape also stops them shifting under load and potentially dislodging a marginal gear placement. The locking gate adds a final element of security to the system.