- Indicates that there is safe water all around the mark. Can be used as centre-line, landfall or mid-channel marks
- Red and White Vertical Stripes
- Topmark - 1 red ball but only on spar and pillar marks..
- Light, if any, is a white isophase (equal light and dark)
- Or Light may be white occulting (more light than dark)
- Or Light may be single long flash every 10 seconds L Fl 10s
- Or Light may be Morse Code “A” (short-long or . -)