I don't like UV filters. The cap won't fit over the bare filter adapter?
Sorry I never responded back to this. Yes the cap does fit over the bare filter adapter. It works great. Fotasy X100B 49mm filter adapter and CamDesign 49mm lens cap : ) Not bad for $14 bucks total.
I ended up taking off my UV filter when I realized the cap fits, as I also don't like using filters.