Used during long sleeps or night time. Dedicated night nappies, and day nappies that can be boosted for night time are listed here.
For a thorough breakdown of night nappies check out the 'Cloth at night' blog series on my nappy tips blog: Start on this link (copy and paste in your browser) http://www.beansproutbubba.com.au/blog/2010/05/31/cloth-at-night-an-introduction/