The components are:
- L6x Lamp Module. If it's a three-SF123A light it'll have the P90 Lamp Assembly making it the L69 Lamp Module. Note that I don't believe this is stock item.
- A15 Offset Adapter with M26 mount for the front strut of the front sight casting of M16/AR15 variants
- A21 Universal Housing Body [which forms part of the:]
- UxxT switch assembly. Note that xx is the length of the tape pressure switch cable in whole inches. "T" indicates the flag switch is for Constant-on/off. (BTW, if the flag switch is for disabling the tape pressure switch then it'd be UxxS)
I suppose it is closest to the model 676 which features the L36, A15 & M26, U05.
On that basis I would hazard that a model number could be 976T.
However, if you asked me what that was, I'd say:
L39, A15 & M26, A12, U05T