i bought a new airlock the other day, same style as the first one i got, just your general 3-piece airlock. thing about this one is there is a white rubber ring inside.i have never seen this before and i tried doing some homework and cant find similar things anywhere. im a pretty mechanically inclined guy, and logically it doesnt make any sense because i would think it would stop the bobber from lifting. can anyone shed light on this for me? whats it for? has anyone seen this before, or is it just a factory screw-up?