The one with the coloured segment that is.
It was in my carry-on bag, and on the X-Ray it must have looked like a blade or something...
They pulled the bag, asked permission to seach it, then pulled out the MINI keyring.
They handled it as it it might go off any minute...
Until they saw what it was....then they just smiled and I was on my way
I upgraded to the loop keyring shortly afterwards, and no more customs worries :
Chris.