They all work that way. A line is a line. They can be very faint.The control line is usually pretty obvious.
killerweed420 Reviewed by killerweed420 on . Guardian Home Test I tried a strip today. The instructions say it doesn't matter how the line is..."a line is a line". Well, at first I only saw one line, but when I looked closer I could see a second line, which indicated negative. The second line was VERY light, so light that I had to look close; but it was there. The last time I tried it the second line was light, but very noticeable. Does anyone have any knowledge of this and if the very, very light line means I could have an issue even though they say Rating: 5