Even though it is a practical way to assess one's Nitric Oxide (N::O.) levels, it seems to be a $ expensive way to do so if one's purchases them separately since from what I can assess by reading HumanN.com information, it can cost close to $15 for 5 of this strips. Since I believe in NEO40 after reading a lot of information about it, I am a subscriber of it so I get a periodic 6 months supply @ a time which comes with this 5 strips as a bonus (gratis) & it is reported to be close to a $15 value. I am pleased to get it as bonus so a reward to be a reliable regular customer. If I am incorrect about its cost if one purchases them separately, I would welcome a clarification from HumanN staff.