What are some four letter words with 1st letter S and 3rd letter I and 4th letter S?

According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 4 words with the pattern S-IS. That is, four letter words with 1st letter S and 3rd letter I and 4th letter S. In alphabetical order, they are:

sais

seis

skis

sris