respect
Women are required to wear skirts covering the knees and have their shoulders covered, too. Most of the monastaries do provide wraps for women who come unprepared, but if you bring your own, especially one with bright colors, you'll get a smile from the monk or nun at the entrance.
Along the same line, men are required to wear trousers covering the knees. This too can be borrowed from the stock at the entrance but that clothing isn't washed after every user so it may cause a bad feeling to you wearing these skirts. One size fits all for man!
