The ultra low dose BCP is Alesse contains 20 mcg ethinyl estradiol and 0.1 mg levonorgestrel
Mircette contains 20 mcg ethinyl estradiol and 0.15 mg desogestrel;
These both have many generic available. They say that break through bleeding is common on the ultra low dose but I have never had any on them and I never take them at the same time either. I take them before I go to bed and that is never at the same time. I'm usually anyway from 1-6 hours late. I stopped taking them at the same time after my first year on them when I worked crazy shifts at the casino's. Been like that for over 10 years now. YOU SHOULD TAKE THEM AT THE SAME TIME! Don't do as me I'm a bad example.

Then there are the LOW DOSE FAMILY PILLS:
LoOvral contains 0.03 mg ethinyl estradiol and and 0.3 mg nogestrel

Nordette contains 0.03 mg ethinyl estradiol and 0.15 mg levognorgestrel
Ortho-Cept contains 30 mcg ethinyl estradiol and 0.15 mg desogestrel
Cyclessa is a triphasic oral contraceptive with an estrogen dose as low as 25mcg; the graduated progestin (desogestrel) doses are 0.1, 0.125, and 0.15 mg in weeks 1, 2, and 3.
Yasmin contains 30 mcg of estrogen and 3.0 mg of drospirenone, a novel progestin that is more similar to natural progesterone.

EDIT:1 g = 1000 mg 1 mg = 1000 mcg . So, a dosage in mg's will have a thousand times more medicine than the same value in mcg's

I should not say never had break through I have from time to time but it's never really been an issue with me.