That bulb, the "10 Watt", is powered without problems with 2 x RCR123 cells.
I have used the "15 Watt" edition, also from DX, on 2 x RCR123.
Be aware there is a problem with these because the outer spring not easily gets down the throat of the adapter when used together with the E2C-adapter Lighthound and TnC sold.
You might want to "help" the spring down the throat when installing it, to make good contact between the spring and the top of the battery tube when using an E-body and the E2C-adapter.
In a 6/9P there should be no problems.
Lumens Factory bulbs showed no such problems, but their spring on the D26 lamp-assemblies is different from the DX lamp-assemblies.
Just some info should you start assembling a host with Surefire E-body, E2C-adapter, and C2/3 bezel or 6/9P-bezel.