I have one for a T10/15 and it fits my Fenix L2D heads (sort of) fine.
However, the design of the diffuser is goofy - it isn't secure like a SureFire. It has these silly lugs toward the head that hold it on - and certainly not securely. The diameter is too big and there's a gap between the diffuser and body behind the lugs. I can only guess they designed it this way to fit multiple diameter bodies.
In general, I'd say pass on this item :thumbsdow