Teaser/Mailer Length

I am starting to put together a Teaser and Portfolio, to look of a summer internship/co-op. Is there a certain length that is accepted for a teaser/mailer? I was only going to do a one page teaser, but looking on the boards here it seems that having a much longer one is very common, say 4-7 pages.

Secondly is there a “wrong” size of teaser my thought was 11x17 format as that allows a decent amount of space and is still manageable, would it make more sense to have a 8.5x11 for a mailer?

Here is the current Teaser, any feedback would be great.

I’m going to do 11x14 ( same as my full portfolio). With my resume page, the teaser I’m working with now is about 13 pages.