Features: ST-100-Pro Underwater Strobe suitable for most of Seafrogs and Meikon camera cases which have the optical fiber interface. ST-100 Pro and TTL is only compatible with Nikon camera, connected by USB. Max. diving depth is up to 100m/328ft, it can be used at water temperature between 0 and 40. Powered by 4 * AA alkiline or nickel metal hydride(NiMH) batteries, use new batteries only.(Batteries are not included.) Before using the equipment underwater, check that the unit is watertight and ready for use. Specifications: Brand: Sea frogs Material: PC Flashing Index: GN: 32 (overload ISO100) Digital Support: Optic Cable (compatible with all cameras) Digital Support: USB Cable (compatible for Nikon camera TTL) Flash Point: 100 x 100 Battery: 1.5V alkaline/ AA battery/ 1.2V nickel metal hydride/ AA batteryNot included) Flash Time: AA alkiline battery: 500 times / AA nickel metal hydride battery: 600 times Reflect Speed: 5s (alkaline) / 4s (nickel metal hydride) Flash Support: Support 5 pin socket & optic cable connection Reflect Instructions: LED light (red) Color Temperature: 5600K Focusing Light: 3W LED, manual/auto (auto 8s close), auto close when exposure Pressure Depth: 100m/328ft Exposure Control: optical cable/ USB synchronize with TTL, adjust the luminosity (flash index), M grade by turnable button Index Grades: 11 grade (GN1 / 1.4 / 2.8 / 4 / 5 / 5.6 / 8 / 11 / 16 / 22 / 32) TTL Compensation: 11 stage (EV -0.3 / -0.7 / -1.0 / -1.5 / -2.0 / 0) (+0.3 / +0.7 / +1.0 / +1.5 / +2.0 ) Dimensions: 105 * 163 * 98mm Package Size: 22.0 * 19.0 * 11.5cm / 8.7 * 7.5 * 4.5in Package Weight: 1090g / 38.4oz Package List: 1 * ST-100-Pro Strobe 1 * Optic Cable 2 * Soft Light Len 1 * User Manual(English, Chinese)