The Straw Hat Grand Fleet is a fleet formed by seven organizations who vowed to serve under Monkey D. Luffy and the Straw Hat Pirates.
All seven leaders are extremely powerful and formidable fighters with five of them being strong enough to defeat executives of the Donquixote Pirates.
In One Piece SBS Oda revealed the age of all the StrawHat Grand Fleet Captains:
D: “Oda-Sensei Hello! How old is Sai? How many years separate him and his bride?”
O: “It’s fine, Sai’s age is… No, I will show you the ages of all those received a child sake cup.
Sai is young, did he seem so old to you?”