A research pen is a reusable metal instrument that holds a standard 3 ml (300-unit) glass cartridge and dispenses a set volume in 0.01 ml increments, read off a unit counter window. PreppinPeppers stocks four: the Gansulin click-dial pen and the V1, V2 and V3 draw-and-push pens. All four take the same standard cartridges, with no proprietary refills.
What a cartridge pen is, and what it is not
A cartridge pen is a mechanical metering device. It clamps a 3 ml glass cartridge in a barrel, advances the cartridge plunger by a fixed distance for every unit set on the dial, and holds that setting until it is dispensed. No electronics, no battery, no firmware. The repeatability comes from the lead-screw pitch and the detent mechanism, which is why an all-metal chassis behaves differently over a few hundred cycles than a moulded plastic one does.
What it is not is a volumetric instrument with a traceable accuracy claim. These are laboratory and educational hardware. If a protocol needs documented volumetric accuracy, a calibrated positive-displacement pipette is the correct tool and a pen is not. We would rather say that here than have you find out at the bench.
The four pens, and how to choose between them
Gansulin click-dial
All-metal body, 1 to 60 units, one audible and tactile click per unit. It is the only pen here with an overdraw interlock, meaning the dial stops when the setting would exceed what is left in the cartridge, and with dial-back correction, meaning a mis-set count can be wound back without expelling anything. Ships with a zip case. Choose the Gansulin pen if you set many different volumes and want a misdial caught by the mechanism rather than by noticing it afterwards.
Do not choose it if you set the same volume every time and never need to correct. The interlock and the dial-back are what you are paying the step up for, and a single-volume workflow never touches either one.
V1, 80-unit
Metal body, draw-and-push: pull the end knob out to set the dose, at which point the graduated scale extends and the counter window reads the units, then push the knob in to dispense. The V1 pen is the only one here that reaches 80 units in a single draw. Traditional clip cap, closed end.
Do not choose it if your largest single draw sits comfortably under 60 units. The extra range is the whole reason the V1 exists. Note also that it takes the short-stopper variant of the standard 3 ml cartridge, which is worth checking against cartridges you already hold before ordering.
V2, 60-unit needle-shield
Aluminium, 16 cm by 1.86 cm, draw-and-push. The V2 pen has an open spring-end that shields the needle area, so there is no cap to remove and refit; the pocket clip sits on the body instead.
Do not choose it if you want a capped pen for a drawer or a coat pocket. The open end is the design rather than an omission, and it is a straight trade against having a clip cap.
V3, 60-unit aluminium alloy
Aluminium alloy, clip cap, updated internal build. The V3 pen has the same 60-unit range, the same 0.01 ml increment and the same draw-and-push action as the V2, in a slimmer capped body. Between the two, decide on the end design alone: shielded open end, or capped with a clip.
Is there a V4 research pen?
No. There is no V4 pen in this catalogue and we do not stock one. The line is V1, V2 and V3 alongside the Gansulin click-dial. The V-numbers are build variants, not a version ladder: a V3 is not a newer V1, it is a different body, end design and dose range. If you have seen a V4 listed somewhere, that is another seller's naming rather than a later model of these.
What the numbers mean at the bench
Units on these pens are U-100 units. 100 units is 1 ml, so one unit is 0.01 ml and a full 3 ml cartridge holds 300 units. A 60-unit pen therefore delivers up to 0.6 ml in a single draw and an 80-unit pen up to 0.8 ml. None of that says anything about mass. Milligrams depend entirely on how much diluent went into the cartridge, which is why an identical 20-unit draw represents two different quantities of material in two differently prepared cartridges.
Compatibility, and why there is no lock-in
Every pen here takes the standard 3 ml / 300-unit glass cartridge, which is the most widely produced pen cartridge format in existence. There is no proprietary consumable. If PreppinPeppers stopped stocking cartridges tomorrow, these pens would keep working with any other standard 3 ml cartridge. The V1 takes the short-stopper variant of that same format.
Needles use a standard screw-on pen-needle interface. We do not include or sell needles. Reconstitution also needs a diluent, which is not part of any pen; bacteriostatic water is stocked separately.
Storage and handling
Keep pens dry and at room temperature. If a pen is going to sit unused for a long stretch, store it with the cartridge removed so the plunger seal is not held under compression. Wipe the cartridge holder rather than immersing the pen: the mechanism is a dry assembly and water in the lead screw is the one thing that reliably ruins it. A dial that starts to feel gritty is almost always residue in the holder rather than wear in the mechanism, and cleaning the holder fixes it.
Specifications
| Cartridge format | Standard 3 ml / 300-unit glass, shared by all four pens. V1 uses the short-stopper variant |
|---|---|
| Dose increment | 0.01 ml, which is one unit on a U-100 scale |
| Dose range | 1 to 60 units (Gansulin, V2, V3); 1 to 80 units (V1) |
| Dose mechanism | Click-dial with overdraw interlock and dial-back (Gansulin); draw-and-push (V1, V2, V3) |
| Body material | Anodized metal (Gansulin, V1); aluminium (V2); aluminium alloy (V3) |
| Needle interface | Standard screw-on pen needles. Needles are not included or sold |
| Reusable | Yes, all four. The cartridge is the only consumable |
| Intended use | Research, educational, and demonstration use only |
Compare and order: the Gansulin click-dial pen, V1 80-unit pen, V2 needle-shield pen and V3 alloy pen each carry their own colour and multi-pen options in the variant picker on the product page, where the current options and pricing are always the live ones. Buying a pen with its cartridges and diluent together is what the starter kits are for.
Common questions
Which cartridges fit these pens?
Standard 3 ml / 300-unit glass pen cartridges, the common format used across cartridge pens. The V1 takes the short-stopper variant of that format. There are no proprietary refills for any pen here.
Is there a V4 research pen?
No. There is no V4 in this catalogue. The range is V1, V2 and V3 plus the Gansulin click-dial pen, and the numbers denote different builds rather than successive versions.
What is the actual difference between the Gansulin pen and the V1, V2 and V3?
Mechanism. The Gansulin pen is a click-dial with one detent per unit, an overdraw interlock and dial-back correction. The V1, V2 and V3 are draw-and-push pens: pull the knob out to set, push it in to dispense. The V1 also reaches 80 units where the others reach 60.
Are needles included?
No. The pens use a standard screw-on pen-needle interface, and needles are not included or sold by us.
How do I compare pricing across the pens?
Open any pen product page and use the variant picker. It always shows the live options and current pricing, including multi-pen options that reduce the cost per pen. We deliberately keep figures out of this description so it cannot go stale.
Are these medical devices?
No. They are laboratory hardware sold for research, educational, and demonstration use only, not sold sterile, and not for human or veterinary use.
From The Lab
Everything in this collection is sold for research, educational, and demonstration use only. Nothing here is a medical device, nothing is sold sterile, and nothing is for human or veterinary use of any kind. Not evaluated by the FDA. Nothing on this page is dosing guidance. 21+.
