Recommendation for an intake fan in a 4x4x7 tent

I have a 4in inline fan exhausting me lamp tent and lamp, and a vertical fan giving a breeze to the girls, however i dont have an intake fan. i have a feeling an intake fan isnt TOO necesarry as there are flaps for air to naturally come in.

However, do you think i need one? If so, which should i go with?

I don't think you'll need one in a little tent like that. If you got your exhaust fan speed high enough so that there is negative pressure it will help to draw air in through the flaps anyways.