Flash Control: With a guide number of 38 (ISO 100), Supports manual(M) and S1/S2 optical control. In M mode, easily adjust flash output from 1/1 to 1/128 in 1/8 stop increments. Note: Dont support TTL, HSS and the camera menu setting Function. Widely Compatible: With single contact point hot shoe, its compatible with Canon Nikon Panasonic Olympus Pentax cameras with standard shoes and also compatible with Sony MI Hot Shoe,like a9 a7 a7II a7III a7R III a7RII a7SII a6000 a6300 a6500 (Not compatible with EOS Rebel SL3/250D Rebel T7/1500D 2000D Rebel T100/3000D 4000D ) Power Management: Switch to the ON, the flash will start charging (the charging indicator is dim) For a test flash, press the test button. After use, press the ON/OFF to OFF to power off Red charging indicator lamp flickers in every 1s; it indicates low battery; The flash unit has 8 steps of power output control which indicated by 8 pieces of LED. Powered by a CR2025 battery.