From the Manufacturer...
The Viper is very stable to overstable disc that is very reliable in all wind conditions. The Viper changed the way disc golf is played by becoming the first disc used for the “Flex Shot”. Excellent choice for sidearm throwers. Recommended for experienced players.
Weight Range: DX:150-180g
Best Choice for: Flex shots, Spike hyzers, Headwind shots
Available Plastics: DX