This is a true ring FLASH. It works just like a regular speedlight, and is bright enough to get a proper exposure of a room at ISO 200 F4 even when bouncing it off the ceiling. It has many of the same features as a speedlight such as TTL, manual, and multi (strobe) mode. Additionally, the ring is split into 2 sides which can be controlled independently through TTL ratios, manual adjustment (eg. Side A 1:1 and Side B 1:4 power), or one/both sides can be turned off. Other features include modelling light, FEB, FEL/FV, rear curtain sync, voice prompt (on/off), 2.9s recycle time, 30minute auto shutoff.There is strong vignetting at 10mm on a sigma 10-20mm, but none at 15mm. On my 18-105mm, there is some vignetting up to 30mm. The modelling light is useful for focusing or in the dark, but this is not a ring light, just 2 small LEDs (NOT for video, only photo). Because of those 2 LEDS, the light is not a full circle. It's more like two 3/4 moons, which can result in weird shadows depending how it's rotated, and depending if you're shooting vertical or horizontal shapes (see photo).The flash is all plastic, but feels prety solid. The head rotates. On the side of the flash is a PC sync port and 3 pin power jack. Included is a case, foot, and 4 rings (52mm, 58mm, 67mm, 77mm). The rings screws on the camera lens, and the the flash clips on.▐ MODES- TTL: This setting is like the camera built in flash, it will try to get a proper exposure regardless of the cameras ISO and shutter speed. Has exposure compensation of 1/3, up to -/+3 stops.- MANUAL: Adjust the power from 1/128 - 1/1 in 1 stop increments using the horizontal buttons, and 1/3 increments using the vertical buttons.- MULTI: A strobe mode that allows you to have the flash fire X number of times per X number of seconds.▐ PROS- TTL- Powerful.- LCD backlight (on/off).- Easy to adjust modes/settings.- Charge beep feedback to notify that it's ready to fire (on/off).- Thick batteries like Eneloop XX and Powerex IMEDION AAs fit fine.- Nice rubber clicky buttons.- Rotatable head and cord allows flash to be held 20 inches off camera.- Modelling lamp.▐ CONS- Only 270' head rotation instead of 360', can't point it over my left shoulder.- Cannot be controlled by camera commander mode.- No battery level indicator.- No high speed sync.- No Master unit control.- Light is not a full circle due to LED lights. It's more like two 3/4 moons.▐ CONTROLSThe controls are easy to use, I figured them out myself.- All modes: Hold On/Off button to power on, off. Press once for LCD backlight. Lamp buttons turns lamp off, focus, or on.- TTL Mode: OK button to change ratio (8:1 - 1:8), ratio button to enable/disable sides A B, left/right arrows to change compensation (-3 - +3 EV).- Manual mode: Press OK to change flash power for side A, again for side B.- Multi Mode: OK Button change power for side A, again for change number of seconds (1-40 seconds), again to change frequency (1-100hz), and again to change power side B. Power settings are changed in 1 stop increments, 1/3 for TTL EV compensation. Settings do not loupe, meaning you cannot go from 1/1 power to 1/128 without going all the way back down through the in between levels. Not a big deal, but I prefer loupe.▐ CONCLUSIONDespite its few cons such as the ring not being a complete circle (the ring effect is good, but not perfect), and no HSS, this is a good ring flash with a few neat features. 4.5 stars. Sample provided for testing and unbiased review.