Foundation weights

If you want it perm then use epoxy. I used silicone and that's what most use. Unless it's got a threaded center, I would assume even silicone is permenent. There was like zero clearance with tungsten and they wouldn't even fit in the 2 nearest holes. No idea how one would get them out.
 
i used a marine epoxy. Was flexible and super solid. Tried a couple different other glues and they would come loose after a match. The marine epoxy is permanent