First response OPKs

[Swee]

Hi!
not sure if anyone has tried this or not. I got first response 20 strip OPKs last month, the one where the digital reader shut off after saying yes. So I had about 10 strips left and decided to use them today ( 6 dpo). Do these strips have a test line built in them? I tried a strip with water and another liquid and no line appeared. Would anyone happen to know?

 

[Dill]

I have no experience with the brand personally, but I've never known an OPKs to NOT have a control line. You need one to tell if your test line is positive or not.