Collimating a f4.5 dob

Hi, I just purchased a rigel aline tool ($8) to collimate my primary mirror. The site I ordered from said it could also be used for the secondary. I don't know if I belive this, Could this work as my only alignment tool? If not, what should I get to compliment this piece?

I have a 16 in scope at f 4.5 so I need the alignment very good.

Thanks, Marc