Feature:1. ST-100-Pro Underwater Strobe suitable for most of Seafrogs and Meikon camera cases which have the optical fiber interface.2. ST-100 Pro and TTL is only compatible with Nikon camera, connected by USB.3. Max. diving depth is up to 100m/328ft, it can be used at water temperature between 0 and 40.4. Powered by 4 * AA alkiline or nickel metal hydride(NiMH) batteries, use new batteries only.(Batteries are not included.)5. Before using the equipment underwater, check that the unit is watertight and ready for use.Specification:Item Type: ST100 Pro Underwater StrobeMaterial: PCFlashing Index: GN: 32 (overload ISO100) Digital Support: Optic Cable (compatible with all cameras) Digital Support: USB Cable (compatible for camera TTL) Flash Point: 100 x 100 Battery: 1.5V / AA battery/ 1.2V / AA batteryNot included) Flash Time: AA alkiline battery: 500 times / AA battery: 600 times Reflect Speed: 5s / 4s 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 key 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 ) Size: Approx. 105 x 163 x 98mm / 4.1 x 6.4 x 3.9in.Package List:1 x ST100 Pro Strobe1 x Optic Cable2 x Soft Light Lens1 x User Manual