No vent holes on chinese incubator

I have a 35$ cheapo incubator for my first hatch, 10 out of 12 eggs have embryos and I'm on day 18. I've seen reviews of this one with fluffy chicks running around inside that also had ducks in the same batch so I think I'm good but there's no obvious ventilation. Unless the lip around the dome is just enough of a crack to draw fresh air around the edges idk. Got some eggs wiggling tonight, removed the auto roller this morning.