The Swiss made Russian retailed Volna watch line was introduced in 2007 with the Typhoon series inspired after the Soviet submarine fleet. The oversized crown actuator provides double security for shock protection and water-resistance. The dial display indicates whether the watch is open or 300M closed. The Typhoon series has three models. The two represented here are the SBDI, Security Big Date Indicator and the SPRI, Security Power Reserve Indicator. The third model is referred to as the SI or Security Indicator.