6-7cells hotwire bulb?

Anyone can suggest a 6-7 Ni-Mh cells hotwire bulb?

ROP High, or 5761.

You need to check out LuxLuthor's thread at the top of this forum about "Destructive Incan Bulb Testing". Find a bulb with the best light output with the voltage that 6 (6*1.2V=7.2V) or 7 (7.8V) NiMH cells would output and run with it. Just make sure your not too close to the edge of blowing it because when you first turn the light on, the sudden voltage spike can be more than the steady voltage listed above.

Are you going bi-pin or I guess by drop-in you mean that it needs to fit the Mag holder. If the latter is the case, the ROP-high is the absolute hands down winner. Check his charts anyways. He tests that bulb as well.