CB Digital (Smart Countdown) - settle the debate?

So I know these shouldn't be cracked open, but I've heard different things in regard to there being two lines on cb digis with smart countdown, the kind with one strip inside. Do these test for lh as well like the digis with week estimator, or is is just hcg? Is there always a second line no matter what? I've heard is just one line sometimes but I know these work differently and are less sensitive.

Note: I got a 'not pregnant' reading, so out of curiosity, wanted to see the strip. I am accepting the negative result, but just want clarification from others who have tested this as well.