Peptide Pen Versions UK — V1 vs V2 vs V3 vs V5 Explained

V1, V2, V3 or V5 — what do peptide pen version numbers actually mean, and which should you buy? The short answer for UK research buyers in 2026: the V3 is the current standard, and the V5 is the newest revision, adding an 80 IU dosing scale and a retracting needle. This guide explains what changed between versions, what stayed the same, and how to choose. Written for laboratory and research purposes only.

Peptide Pen Versions at a Glance

Version	Dosing scale	Key traits	UK availability
V1 / V2	Typically 60 IU	Earlier design iterations of the same 3ml cartridge platform — fewer refinements; exact spec varies by seller	Still sold by some UK retailers at lower prices; increasingly uncommon
V3	60 IU (0.6ml per setting)	Anodised aluminium body, dial-in precision, clear glass cartridge end, universal needle thread, widest colour range (9 colours)	In stock — the current UK research standard
V4	—	Rarely seen in UK retail stock — most UK ranges step straight from V3 to V5	Effectively skipped
V5	80 IU (0.8ml per setting)	Retracting needle (hidden in use), same clear glass cartridge end as V3	Newest version — in stock in the UK

What the V Numbers Actually Mean

There is no official standards body behind peptide pen version numbers. “V1”, “V2”, “V3” and so on are revision numbers of the same underlying device: a reusable pen body that accepts a standard 3ml borosilicate glass cartridge and meters delivery through a click-dial mechanism. Each revision refines the drive mechanism, body construction and usability of the one before it. Because the numbers are a manufacturing convention rather than a certification, always check the actual specification — dosing scale, cartridge format, needle thread — rather than the number alone.

V3 — The Current Standard

The V3 Reusable Peptide Pen Injector is the version most UK research protocols and most UK sellers standardise on. It pairs an anodised aluminium body with a dial mechanism marked to 60 IU (each IU graduation = 0.01ml, so a full dial is 0.6ml), takes standard 3ml glass cartridges behind a clear cartridge end, and accepts any pen needle on the universal ISO thread — including 31G x 6mm and 32G x 4mm. It is available in nine colours, on its own or as a complete Peptide Pen Kit with a cartridge, ten needles and a carry case.

V5 — What Changed

The V5 keeps the V3’s cartridge system entirely — same clear glass cartridge end, same protective cap, same 3ml cartridges — and changes two things:

80 IU dosing scale — a wider range on a single setting than the V3’s 60 IU (0.8ml vs 0.6ml maximum per dial).
Retracting needle — the needle retracts into the pen and stays hidden while the pen is in use.

It launches in four colours (Gunmetal, Teal, Gold, Red), standalone or as the Peptide Pen Kit V5.

V3 vs V5 — Which to Choose

Choose the V3 if you want immediate dispatch, the widest colour choice, or simply the proven standard — it remains fully current and shares its consumables with the V5. Choose the V5 if the wider 80 IU scale or the hidden retracting needle matters to your workflow — both are in stock in the UK. Because both pens take the same cartridges and the same needles, nothing in your consumable stock changes whichever you pick.

What About V1, V2 and V4?

V1 and V2 pens still appear at lower prices from some UK sellers. They work on the same 3ml cartridge principle but predate the refinements that made the V3 the standard, and their exact specification varies by manufacturer batch — if you are buying one, confirm the cartridge format and needle thread before ordering. V4 never established itself in UK retail stock; most ranges, including ours, step directly from V3 to V5.

What About V6?

No V6 peptide pen generation exists in UK retail stock yet — the V5 is the newest version available. When a V6 pen reaches the UK market this guide will be updated to cover it; until then, treat any “V6” listing with the same spec-checking caution as any unverified version claim.

Prefer not to maintain a pen at all? We also stock single-use disposable peptide pens — see the disposable vs reusable guide for choosing between formats.

For single-generation deep-dives, see our dedicated reference sites: V3 pens explained, the V4 story and the V5 generation explained.

Frequently asked questions

Are cartridges interchangeable between peptide pen versions?

Across the V3 and V5, yes — both use the same clear glass cartridge end and take the same standard 3ml glass cartridges. Earlier versions generally use the same 3ml format, but spec varies by seller, so check before buying a V1 or V2.

Do all versions take the same pen needles?

Any pen with the universal ISO needle thread — which includes the V3 and V5 — accepts standard pen needles such as the 31G x 6mm and 32G x 4mm packs. See the peptide needle size guide for choosing between them.

Is the V5 worth it over the V3?

If you need the wider 80 IU dial range or prefer the retracting hidden needle, yes. If immediate availability and colour choice matter more, the V3 is the proven standard and shares all its consumables with the V5 — there is no wrong answer between the two.

What is the best peptide pen version in 2026?

The V3 is the established UK research standard and the V5 is the newest revision. Both are current; earlier versions (V1/V2) are legacy designs that some sellers still stock at lower prices.

Does a higher version number mean the pen is certified or approved?

No. Version numbers are a manufacturing revision convention, not a certification. Reusable peptide pens are supplied as laboratory research equipment, not medical devices.

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⚠️ For laboratory research use only. Not for human clinical use. This content is educational and does not constitute medical advice.