What is the Klow Stack? Composition, ratio and certificate
The short answer. Klow is a four peptide blend supplied as a single lyophilised vial. It contains GHK-Cu, TB-500, BPC-157 and KPV. The name is simply the initials of the four components. In the June 2026 batch an independent laboratory measured the contents at GHK-Cu 54.66 mg, TB-500 11.80 mg, BPC-157 11.18 mg and KPV 10.95 mg, for a total peptide content of 88.59 mg. Those are measured figures from an assay, not label claims, and the report can be checked on the laboratory's own website.
For research purposes only. Not for human consumption. 18+. UK only. This article describes the composition and laboratory testing of research materials. It does not describe effects, uses, dosing or administration, and nothing here is a claim about what any compound does.
What Klow is
Klow is a supply format rather than a scientific category. Four peptides are lyophilised together into one vial instead of being supplied as four separate vials. The compounds themselves are unchanged by being blended.
The name is an initialism of its contents, and it follows directly from an older one. Glow is a three peptide blend of GHK-Cu, BPC-157 and TB-500. Add KPV and you get Klow. That is the entire relationship between the two, and it is the question most people are actually asking when they search for one or the other.
What the blend format changes is practical: one vial rather than four, one reconstitution rather than four, and one certificate covering the combination. It also changes what a laboratory can tell you about the vial, which is covered further down and is the part most suppliers skip.
Measured composition, June 2026 batch
These are the figures returned by Janoshik Analytical for the batch assayed on 23 June 2026. The report number links to the laboratory's own verification page, not to ours.
| Peptide | Measured content | Share of vial |
|---|---|---|
| GHK-Cu | 54.66 mg | 61.7% |
| TB-500 | 11.80 mg | 13.3% |
| BPC-157 | 11.18 mg | 12.6% |
| KPV | 10.95 mg | 12.4% |
| Total peptide content | 88.59 mg | 100% |
Report: #168699, Janoshik Analytical, 23 June 2026.
GHK-Cu makes up nearly two thirds of the vial by mass. This is the single most useful thing to understand about Klow and it is rarely stated plainly. The other three peptides sit close together in the 11 to 12 mg range. A headline figure such as "80 mg" or "90 mg" is not divided evenly between four compounds, and no blend's total should be read as though it were.
That is a function of the compounds rather than a quirk of one supplier. GHK-Cu is conventionally supplied in far larger quantities than BPC-157, TB-500 or KPV, so any blend containing it will be dominated by it.
Klow compared with Glow
Both were assayed from the same June 2026 batch run.
| Glow | Klow | |
|---|---|---|
| Peptides in the vial | 3 | 4 |
| GHK-Cu | 58.44 mg | 54.66 mg |
| TB-500 | 12.65 mg | 11.80 mg |
| BPC-157 | 12.46 mg | 11.18 mg |
| KPV | not included | 10.95 mg |
| Total | 83.55 mg | 88.59 mg |
| Report | #168677 | #168699 |
The three shared peptides sit slightly lower in Klow than in Glow, and KPV accounts for the difference in total. If you are choosing between the two, the practical distinction is the presence of KPV and very little else.
For completeness, the Wolverine Stack is the simpler two peptide blend of BPC-157 and TB-500, measured at 25.12 mg total in the same batch run. All three are set out side by side in what is in a peptide stack.
What the four peptides are
Brief factual descriptions. Each links to a fuller reference page. None of these are statements about effects.
GHK-Cu is a copper binding tripeptide with the sequence glycyl histidyl lysine, complexed with copper. It is the component supplied in the largest quantity in this blend. Reference page: GHK-Cu.
TB-500 is a synthetic fragment of Thymosin Beta-4, a naturally occurring 43 amino acid protein first described in the 1980s. Reference page: TB-500.
BPC-157 is a 15 amino acid peptide, sequence GEPPPGKPADDAGLV, described in the literature as a partial sequence derived from a protein found in gastric juice. Reference page: BPC-157.
KPV is a tripeptide, lysine proline valine, corresponding to the C terminal fragment of alpha melanocyte stimulating hormone. Reference page: KPV.
A neutral comparison of the two most frequently confused components is at BPC-157 vs TB-500.
Why a blend has no single purity percentage
This matters when comparing suppliers, and it is the most common piece of misinformation in this part of the market.
A single peptide vial can be tested two ways at once. Mass spectrometry confirms identity, that the vial contains the compound named on the label. High performance liquid chromatography reports purity, the proportion of the sample that is the target compound rather than impurities. That is where a figure such as 99% comes from.
A vial containing four intended peptides has no single target compound. Chromatography separates four things that are all meant to be there, so there is no basis for expressing the rest as a proportion of one of them. The question simply does not have an answer in that form.
What a blend assay does instead is confirm identity for each peptide present and measure content by mass for each one. That is what the table above is.
So for Klow:
- You can verify which four peptides are in the vial.
- You can verify how much of each, in milligrams.
- You cannot obtain a single HPLC purity percentage, and any supplier quoting one for a multi peptide vial is quoting a number that does not exist.
That last point is a quick and reliable test when comparing sources.
How to check this yourself
None of the figures above need to be taken on trust, which is the point of publishing them.
Each report number links to Janoshik's own verification page. The number is entered there and the result is returned by the laboratory, not by the supplier. If a supplier publishes a certificate as an image with no verifiable report number, there is nothing to check.
A step by step walkthrough of the fields on a report is at how to read a Certificate of Analysis, and the process of confirming one at source is at verify a certificate. Every report is listed at published lab reports.
Common questions
What does Klow stand for? It is an initialism of its four components: KPV, plus the three peptides in Glow, which are GHK-Cu, BPC-157 and TB-500.
What is the difference between Klow and Glow? Klow contains the same three peptides as Glow plus KPV, measured at 10.95 mg in the June 2026 batch. Measured totals were 88.59 mg for Klow and 83.55 mg for Glow.
What is the ratio of peptides in the Klow Stack? In the June 2026 batch, roughly 62% GHK-Cu, 13% TB-500, 13% BPC-157 and 12% KPV by mass. GHK-Cu dominates the vial.
Does the Klow Stack have a Certificate of Analysis? Yes. The June 2026 batch is Janoshik report #168699, verifiable on the laboratory's own site.
Why is there no purity percentage for Klow? Purity by HPLC is the proportion of a sample that is one target compound. A vial with four intended peptides has no single target, so the figure has no meaning for a blend. Blends are tested for identity and content by mass instead.
Is a blend the same as buying the peptides separately? As supplied it is one vial containing four lyophilised peptides rather than four vials. The compounds are the same compounds.
What is used to reconstitute it? The same as any lyophilised research material. Bacteriostatic water is used where a vial will be drawn from more than once. Reference page: bacteriostatic water.
Where to look next
About the author
Sebastian Reuters is a science and health writer working with BioHack London on research-orientation content. He covers analytical methodology, regulatory landscape, and supplier-evaluation topics for the UK research community.