Nitecore Carbon Battery 6K Extended Headlamp Runtime Kit for NU43, NU45, NU53 and HC60 UHE, HC65 UHE, HC70 UHE, and HC75 UHE Headlamps

Looks great and works fine with my NU43. Haven’t had the chance to try battery life yet on it though.

Needs a top strap that works on it

The strap you need to use for this kit is incompatible with the top head strap which makes heavier headlamps like the Nitecore HC75 UHE more practical. I have tried the Nitecore HC75 UHE on the 6K Extended Headlamp Runtime Kit's and it slips down my head and tugs on my hair because of the weight. I recommend for heavier headlamps like the HC75 to just buy extra batteries and switch them instead (unless you aren't able to and need constant light for the extended run time)

Haven’t really put it to the test yet. Like the fact it integrates well with the headlight and serves multiple tasks.