The solution to the incorrect height of the battery adapter problem for the Gossen Lunasix 3 is to remove the small spring/washer insert from within the threaded battery cap from the Lunasix 3. I had the same problem when trying to insert the Gossen Lunasix 3 battery adapter and 2 x SR44 into my light meter last night. I could not get the battery closed or even started on the thread and ended up denting one of the batteries. I then had a good look at the battery cap and could see that the spring/washer that sits inside the cap can be removed. I removed the spring/washer without damaging it by pulling it out of the battery cap with my finger nail, a pair of tweezers could also be used if you do not have long finger nails. After removing the spring/washer from the threaded battery cap the battery cap can now be easily screwed into the light meter with the battery adapter and batteries.