Whirlfloc is a blend of Irish Moss and purified Carrageenan.
Whirlfloc helps to flocculate proteins and particles that cause cloudiness / haze in your beer.
Once dissolved it will bind to proteins present in the wort, helping them to settle out.
Result is a clear wort prior to fermentation.
Add ½ tablet per circa. 23Ltrs during the last 10 minutes of the boil.