This is a perfect charger to pair with your Ledlenser headlamp. I've used this up at our cabin while turkey hunting. I put my headlamp in this case at night and it is fully charged and ready to go each morning. I still always carry some AA's in the field for emergencies but this case has proved to be very convenient. When it runs out of charge, I can plug it into a solar charger to get it back up to charge (our cabin is off grid, have one solar panel with a deep cycle 12V battery). Again having this case has been super convenient for me paired with the use of the MH8 headlamp.
When not at the cabin I can charge my airpods, phone, and other electronic devices. I've brought this on the airplane and it's super convenient to keep everything running when not around an outlet.
Downside for in the field hunting use is that it's a little bulky. I don't think it is a good option for the field or that this case is meant to be used that way. It is best suited for keeping at camp and charging things up overnight, bringing on trips etc.
I got this specifically for the headlamp (bonus is that it works will charging all your electronics by the ports in the front). If your plan is also to pair with a headlamp I'd suggest getting a headlamp that is both rechargeable and can handle AA's so you can have a light weight backup if your headlamp loses power in the field. The case again is not the best option for charging in the field. If you're out of power and trying to hike out somewhere you need an immediate full charge which is what the AA's will do. This charger is perfect for camp to get you to full charge while you sleep. It will save you money in batteries in the long run.
Hope this helps!