Swiss wrestling matches take place in a circular area covered in sawdust and measuring 7-14 metres in diameter. The two opponents wear jute wrestling shorts over their clothes. The wrestlers hold each other by their shorts and try to throw their opponent off balance. The winner is the one who manages to throw his opponent onto his back in the sawdust while holding on to his shorts with at least one hand.
By tradition, at the end of the match the winner brushes the sawdust off the loser's back. There are no weight classes.
Source: wikipedia