Specifications:
Cost: ~$37 (Ali-e, Ali) (at time of purchase: ~$30)
Construction: anodized aluminum
Size: 136 x 40 x 25mm (length x head diameter x tube diameter)
Imperial units: 5.35'' x 1.6'' x 1''
Weight: 165g / 5.8 ounces (without battery). 243g / 8.6oz (w/battery & bolt snap)
UI (User Interface): tailcap Twisty. 3 modes (Hi, Medium, and Strobe)
Powered by: (1) 18650 Li-ion cell
LED: (1) Cree XM-L T6 with smooth (SMO) reflector
Current Draw: 2.6A (advertised)
Burn Time: 3.5 hrs with 3400mAh Panasonic. advertised - 60 min with 2600mAh cell
Working Voltage: 2.7- 4.2V
Depth rating: 150-200m (492-656ft) spec. taken from here
Each Category below gets a 1-5 star rating (*****)
* UI (User Interface): Twisty. The light is operated by twisting the tailcap. This is a small section and it can be a little hard to turn On. It would be much better if the tailcap were bigger.
I don't like the user interface at all. It's a tailcap operated twisty. Many dive lights use the head for twisting and that is much easier. The compact design makes it even more difficult to get a good grasp on the tiny tailcap, especially when you're diving in water and wearing 3mm neoprene gloves - think about it 
It has 3 modes with mode memory. Hi/Med/Strobe (not SOS as advertised). To change modes - with the light ON just twist off and back on to cycle through all the modes.
** Design: It is a compact designed dive light. Size is just over 5 inches long and weight comes in at about 6.5 ounces with battery.
Anodization is a dull black color like the Brinyte DIV05. What type of anodizing I don't know (Type II/III)? But where I tied a boltsnap to the tailcap the anodization is wearing off.
The cooling fins should easily do their job underwater...
Added fins increase the surface area and can radiate the internal heat to the water passing by. Since water is a more efficient conductor than air, it can better dissipate heat away from the light when the LED is properly heatsinked.
The tailcap uses 3 o-rings, which is good for sealing, but it easily becomes harder to twist on/off as the lubrication wears down...
The front bezel unscrews which may give access to the LED. But also could leak here if the bezel was not tightened down snug or if these o-rings fail.
Burn Time & Brightness: 3.5 hrs with unprotected Panasonic cell (3400mAh). Of course at over 3 hours the light is pretty diminished - but it's still on.
Uses a cool white Cree XM-L emitter, with a brightness bin of T6.
* Value: I'm not very happy about the user interface (how it turns on & off with the different modes). And from the time I bought the light the price has gone UP instead of down.
I think the Maxtoch DI6X-4 (Ali) & Dakstar (DT16B) would be very similar dive lights.
Hi-max/X-Beam has some other dive lights that you might check out. But many are high priced even though they are Chinese lights (see hi-maxmall, Ali)
Alternative: I really would like to test X-Beam 110100 model. It's a little high priced (see Ali, eBay).
Conclusion:
I rate the light 
Low rating mainly because the tailcap twisty can be hard to operate and the higher price.
