How many units does a peptide pen hold?

A full 3 mL cartridge holds 300 units. One unit is 0.01 mL, the same scale as a U-100 insulin syringe, and the pen delivers up to 60 units (0.6 mL) at a time. To turn milligrams into units for your vial, use our peptide reconstitution calculator.

What comes in the Starter Kit?

The pen, five empty 3 mL cartridges, 50 pen tips and a hard case. The Pen only option is the pen with its cap.

How do you fill a peptide pen cartridge?

Reconstitute the vial with bacteriostatic water such as Research Water, draw the solution into a syringe and inject it into an empty cartridge through its rubber seal. Load the cartridge, screw on a new pen tip and prime the pen with a 2-unit shot until a drop appears.

Which pen tips fit the Simms Injection Pen?

Standard screw-on pen needles, the same type used on insulin pens. Use a new tip each time.

How should a peptide pen be stored?

Empty, the pen keeps at room temperature. Loaded, it holds reconstituted peptide, so keep it in the refrigerator at 36–46°F (2–8°C) with the cap on and the pen tip removed, and use the cartridge within 28 days. More in our guide, Do peptides need to be refrigerated?

Is the Simms Injection Pen for human use?

No. It is sold for laboratory research use only.

Simms Injection Pen, a reusable ice-blue peptide pen with a black cap, beside its card: 3 mL cartridge, 1–60 units, 1-unit steps

Reusable pen injector

Simms Injection Pen

The Simms Injection Pen is a reusable peptide pen injector for standard 3 mL cartridges. Its dose knob measures in single units from 1 to 60, so every dose is dialed and clicked instead of drawn by eye.

$89.00

Reusable 3mL cartridges 1–60 units

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Product Information

Specifications, storage and care

What it is

What is a Peptide Pen?

Class: Reusable pen injector
Also known as: Peptide injection pen, pen injector
Form: Refillable metal pen
Use: Research use only

Specifications

Peptide Pen Specifications

Cartridge: Standard 3 mL glass (300 units)
Dose range: 1–60 units per dose
Increment: 1 unit (0.01 mL)
Pen tips: Standard screw-on pen needles
Finish: Ice blue metal, black cap
Pen only: Pen with cap
Starter Kit: Pen, 5 cartridges, 50 pen tips, case

Storage

Storage & Care

Room temperature when empty
Cap on
Pen tip off

Pen (empty) Room temperature Dry, cap on, away from heat

Loaded cartridge 2–8°C (36–46°F) Refrigerate · use within 28 days

Peptide Pen Overview

A reusable pen that measures reconstituted peptide in single-unit clicks, from 1 to 60 units.

How it works

The pen holds a standard 3 mL glass cartridge. Turning the dose knob sets the amount in 1-unit steps of 0.01 mL, the same scale as a U-100 insulin syringe, up to 60 units at a time; pressing the knob delivers it through a screw-on pen tip. A full cartridge holds 300 units, so one preparation covers many doses and the pen itself is reused cartridge after cartridge.

Research applications

The pen is used for repeated, measured doses from one reconstituted vial, as in daily or weekly protocols with retatrutide and tirzepatide. Mix the vial with Research Water, fill a cartridge, and use our peptide calculator to turn milligrams into units.

FAQs

What is a peptide pen?

A reusable pen injector that holds a 3 mL cartridge of reconstituted peptide and measures each dose with a dial. The Simms Injection Pen sets doses in single units, from 1 to 60.
How many units does a peptide pen hold?

A full 3 mL cartridge holds 300 units. One unit is 0.01 mL, the same scale as a U-100 insulin syringe, and the pen delivers up to 60 units (0.6 mL) at a time. To turn milligrams into units for your vial, use our peptide reconstitution calculator.
What comes in the Starter Kit?

The pen, five empty 3 mL cartridges, 50 pen tips and a hard case. The Pen only option is the pen with its cap.
How do you fill a peptide pen cartridge?

Reconstitute the vial with bacteriostatic water such as Research Water, draw the solution into a syringe and inject it into an empty cartridge through its rubber seal. Load the cartridge, screw on a new pen tip and prime the pen with a 2-unit shot until a drop appears.
Which pen tips fit the Simms Injection Pen?

Standard screw-on pen needles, the same type used on insulin pens. Use a new tip each time.
How should a peptide pen be stored?

Empty, the pen keeps at room temperature. Loaded, it holds reconstituted peptide, so keep it in the refrigerator at 36–46°F (2–8°C) with the cap on and the pen tip removed, and use the cartridge within 28 days. More in our guide, Do peptides need to be refrigerated?
Is the Simms Injection Pen for human use?

No. It is sold for laboratory research use only.