When you've used it a lot and it has gotten worn out and don't turn as much to the left any more, it's very useful for long, low and straight throws. Both the Viper and the Whippet are easier to control when they have been used and worn for awhile. These are discs where the rim has been grinded down to make them less stable. XD Low profile version of the Aviar. It's less stable and it flies longer than the aviar.
Some players use it for rollers.
Also a good all-around golf disc. Zephyr Lynx-sized with a flat edge. Nice control for approach shots.