The flash unit has 8 steps of power output control which indicated by 8 pieces of LED the MODE key to M Mode. In this mode, you can set TT560 On to your camera hot shoe or speedlite trigger hot shoe to trigger the flash unit. When , adjust the flash power and the camera shutter, the flash light flash under the camera synchronous signal the MODE key to S1 Mode. The Mode is applicable for slave flash in order to create many lighting effects. It is respectively applicable for manual flash environment the MODE key to S2 Mode. The mode is applicable for slave flash in order to create many lighting effects. It is respectively applicable for TTL flash environment. The flash unit 't flash synchronously with the first flash but the second flash from the master flash To prevent the flash head from too hot and damage, please do not flash over 20 times when in power lever 1/2,1/1. Please cool down the flash unit for at least 10 minutes. The over-temperature protection function be activated if you continue to flash after 20 times. In this state the charging time turn to 10-25s Power Management (1) Switch to the ON, the flash charging (the charging indicator is dim). After several seconds, the charging indicator turns red and TT560 is ready to . (2) For a test flash, the test button. After use, the ON/OFF to OFF to power off. (3) If the red charging indicator lamp flickers in every 1s, it indicates low battery. In such case, the power turn off automatically and you need to replace the batteries. Guide Number:38 (m ISO 100 ) (The product printed words depending on the batch, but this does not affect use) Flash Mode: M, S1, S2 Vertical Rotation Angle: 0~90 degrees Horizontal Rotation Angle: 0~270 degrees Power: 4xAAsize batteries ( Alkaline or Ni- are usable ) Lighting Times: 100-1500 times ( AA alkaline batteries used ) Recycle Time: 0.1-5s ( AA alkaline batteries used ) Light Quantity Output Control: with 1/8 - stop increment Color Temperature: 5600K Flash Duration: 1/300s~1/20000s Color: As Shown Material: plastic Package Contents: 1 * TT560 Flash Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.