nothing? 
give the one i linked above a try 
way less bulky than the original, 19 g vs 51 g (not as sturdy of course, but looks still ok to me) and the silicone rings are less tight
O M G!!!
I just received my Astrolux S1… its short tube matches perfectly the threads of the Skilhunt!
I had never heard about that! I can’t believe no one have tried this before :s as you can see there’s the same problem of the orings that are way out of place, but it’s still an awesome surprise for me! 
…and here is this weird frankenstein 
