Vortex Switchview SV-1 Select Viper Throw Levers attach to the magnification dials on Vortex scopes. This throw lever maximizes your efficiency in dialing in to scope out your target. Constructed of lightweight, anodized aluminum for a durable scope accessory. This throw lever is compatible with magnification rings of 1.669 inches or 42mm. If your scope is not a Vortex scope but has a ring that size, this may also work for your scope.