What do you call those mobile pieces?

In pasang, each player has only one mobile piece. This piece is called a "kas". A "kas". Singular, despite the 's' at the end.

"Kas" is a Malay word. What to call it in English? "Kas" is the most obvious choice. Pasang Emas uses "kas" in its help document.

The word "ka" (plural "kas") is used in the Wikipedia entry for pasang (en.wikipedia.org/wiki/Pasang). This was picked up by The Brunei Times.

So, what is it? "Ka" or "kas"? Just accept both. No war!