Yeah I think it's to do with the centre input barb being 5/8" not 1/2". Obviously I know how large it is cause it's in front of me, but seeing pics I guess the barb size is the only part that can be related to, and most folks have either 1/2" or 3/8" on their blocks.
Just to show how simple it is to mess up the look of the block I fitted a 12mm festo push fit for the input, (I couldn't use it like this as it would be to restrictive), but I think it ruins the looks completely myself.
