Community › Dosing & Titration

Pen thread

15 replies13 peopleJul 15, 2026☆ Follow
Summary

which peptide pens work reliably and how do their plunger mechanisms compare across models

Users report that many V-series pens require a cartridge inserted before the plunger will extend or function. Several people tested V1 and similar models after initial failures and found them operational once loaded. Others settled on Novo-style pens with adapters after V3 units proved unusable even with cartridges. Discussions reference visual differences in build quality versus prescription versions and note mostly plastic construction in newer models.

What this discussion establishesWhere people disagree

Whether V3 pens are generally functional or frequently defective even when loaded correctly

Still open

Which specific cartridge types are compatible with V4 pens

Nothing here is advice.

15 replies · 13 people
SteadySignal83archiveopening postJul 15

Starting mostly for US users though someone else posted something similar not long ago. Want to pull together details on pens for myself and to share. Recently got what appear to be v3 pens from an online marketplace and they failed right away; the plunger could not overcome gravity let alone move fluid. Also noticed the pictured pen marked V1 resembles certain other styles. Curious about mechanism details and differences across any brands tried. Checked a friend's prescription version and its internals looked substantially stronger. What pens are others using, how does the plunger appear, and was the cost justified?

LikeSame experienceReply
PatientHarbour49archiveJul 15

It only starts working after I slide the container inside the injector.

LikeSame experienceReply
SteadySignal83archiveJul 15
↳ replying to @PatientHarbour49

Honestly feels like you're just trying to provoke, but even if a vial were inserted the plunger still refuses to come out on its own.

LikeSame experienceReply
BlueSignal49archiveJul 16
↳ replying to @SteadySignal83

Not trying to provoke. The V series pens simply will not advance the plunger unless a cartridge is present inside.

LikeSame experienceReply
WarmAnchor55archiveJul 16

Picked up one just like the first pictured unit. Thought it was defective and reached out to the seller. They explained the same requirement about needing a cartridge. Once loaded it performed properly so I ordered several additional units.

LikeSame experienceReply
PlainMarble21archiveJul 16

Look into the pens discussed on peptide critic's channel along with the ones sold there. Tried a V4 from that source and it seems okay though the mostly plastic build was unexpected.

LikeSame experienceReply
ClearSignal10archiveJul 18
↳ replying to @PlainMarble21

Considering the V4. Assuming the 3 ml vials used in other pens will fit. The source mentioned vials but did not confirm compatibility with the V4.

LikeSame experienceReply
LevelAlder29archiveJul 22

These existing threads cover both how to use pens and user opinions on various makes and models.

LikeSame experienceReply
SteadySignal83archiveAug 3

Ended up choosing a Novo pen 4 with an adapter. The v3 pens would not function at all even when loaded. Also ordered some Gansulin units and will report back on how they perform.

LikeSame experienceReply
NorthQuill51archiveAug 3
↳ replying to @SteadySignal83

Some people make statements like that without considering they might be making an error in setup. Plenty of users run v3 pens without issues.

LikeSame experienceReply
SlowBramble67archiveAug 4
↳ replying to @SteadySignal83

No need to share more if the chosen pen works for you. Most here already know the common models, their quality, and operation. The linked threads and videos cover it.

LikeSame experienceReply
GreenMeadow27archiveAug 4

Those usually run closer to twenty or less. Thirty feels high. Big fan of the V1 myself. Also like the Convi though they have become difficult to locate lately.

LikeSame experienceReply
ClearWillow59archiveAug 4
↳ replying to @BlueSignal49

My V1 units do advance the plunger, though it requires quite a bit of dialing and pressing due to the small dose steps.

LikeSame experienceReply
QuietAnchor73archiveAug 4
↳ replying to @GreenMeadow27

Seeing some of those models reappear, so maybe the shortage is ending.

LikeSame experienceReply
SlowThistle88archiveAug 6
↳ replying to @QuietAnchor73

Have developed a real preference for Convipens and now own nine with three more on the way just to have spares ready.

LikeSame experienceReply
QuietAnchor73archiveAug 6
↳ replying to @SlowThistle88

Regardless of the pen chosen, quality cartridges make the biggest difference for accuracy and how long everything lasts. The lowest-cost cartridges tend to cause problems over time.

LikeSame experienceReply

Add your experience

If you have tried it, this topic is still open. Sign in to reply — it takes a minute.

Sign inCreate an account