Thats perfect for a 3ft tall cage.
If you are going to go for a 4ft, you are going to need a 6% T5 HO.
If you are going for something huge like a 6ft, you are going to need 12% T5 HO
And if you are going to try grow some high light plants You will need a quad T5HO, with at least 1 12% in it.