I am going to the funeral of a close friend's sister; the family is Jewish. In the funeral notice it states: "Gentlemen please wear head covering".
My question is: what is an appropriate covering for non-Jewish gentlemen or men?
There is no religious requirement in Judaism for a non-Jewish man to wear a head covering. However, since a public request was made, some attendees might feel that it is disrespectful or insensitive to appear without a head covering. As a practical concern, and out of sensitivity to the family, I would therefore recommend wearing a head covering. Either a yarmulke or a type of hat that would generally be considered appropriate attire at a funeral should be fine.
a yarmulke also called a kipa is appropriate or a gentleman's hat of some variety (although I don't recommend one that will stand out too much such as a large top hat)