# 3 ml glass cartridges explained: the 300-unit standard, seals and storage - facts

Canonical page: https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained
Type: Lab article

## TL;DR

A 3 ml glass pen cartridge holds 300 units on the U-100 scale. How its borosilicate barrel and two seals work, and why stopper length decides the fit.

## Facts Index

| Fact ID | Category | Entity | Attribute | Value | Source | Evidence |
|---|---|---|---|---|---|---|
| 3ml-glass-cartridges-explained:title | identity | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | title | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) | https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained |
| 3ml-glass-cartridges-explained:published | identity | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | published | 2026-08-06 | Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) | https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained |
| 3ml-glass-cartridges-explained:author | identity | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | author | Preppin' Peppers Editorial Team | Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) | https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained |
| 3ml-glass-cartridges-explained:topics | identity | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | topics | 3ml, cartridge, Evergreen, guide, Guides | Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) | https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained |
| 3ml-glass-cartridges-explained:summary | content | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | summary | A 3 ml glass pen cartridge holds 300 units on the U-100 scale. How its borosilicate barrel and two seals work, and why stopper length decides the fit. | Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) | https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained |
| 3ml-glass-cartridges-explained:section-1 | content | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | section | What it is | Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) | https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained |
| 3ml-glass-cartridges-explained:section-2 | content | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | section | Why the format is standard | Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) | https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained |
| 3ml-glass-cartridges-explained:section-3 | content | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | section | The two seals | Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) | https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained |
| 3ml-glass-cartridges-explained:section-4 | content | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | section | Individually pouch-sealed | Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) | https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained |
| 3ml-glass-cartridges-explained:section-5 | content | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | section | Storing sealed cartridges | Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) | https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained |
| 3ml-glass-cartridges-explained:section-7 | content | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | section | What the research community gets wrong about 3 ml glass cartridges | Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) | https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained |
| 3ml-glass-cartridges-explained:product-gansulin-metal-peptide-pen | products | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | references product | Gansulin Pen · Reusable Click-Dial, 3 ml (1-60 Units) | Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) | https://www.preppinpeppers.com/products/gansulin-metal-peptide-pen |
| 3ml-glass-cartridges-explained:product-gansulin-3ml-cartridge | products | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | references product | Gansulin-Compatible 3 ml Glass Cartridge for Pens (10-Pack) | Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) | https://www.preppinpeppers.com/products/gansulin-3ml-cartridge |
| 3ml-glass-cartridges-explained:source-www-schott-pharma-com | source | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | cites | SCHOTT Pharma , Pharmaceutical Cartridges (FIOLAX Type I borosilicate glass, ISO-standardized 1.5/3/5/10/20 ml, pen and auto-injector compatible) - www.schott-pharma.com | Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) | https://www.schott-pharma.com/en/products/pharmaceutical-cartridges |
| 3ml-glass-cartridges-explained:source-www-westpharma-com | source | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | cites | West Pharmaceutical Services , USP <660> Containers, Glass revision (Type I glass and hydrolytic resistance, performance-based classification) - www.westpharma.com | Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) | https://www.westpharma.com/blog/2023/october/usp-revision-glass-container-vials-packaging-chapter-660 |
| 3ml-glass-cartridges-explained:source-endolab-org | source | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | cites | EndoLab , ISO 13926-1 (dimensions, material, leakage, and hydrolytic resistance for glass cylinders used in pen injectors) - endolab.org | Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) | https://endolab.org/instruments/iso-13926-1/ |
| 3ml-glass-cartridges-explained:source-pubmed-ncbi-nlm-nih-gov | source | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | cites | Jenke, Expert Opin Drug Deliv 2014: Extractables and leachables considerations for prefilled syringes - pubmed.ncbi.nlm.nih.gov | Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) | https://pubmed.ncbi.nlm.nih.gov/24955780/ |
| 3ml-glass-cartridges-explained:source-www-sigmaaldrich-com | source | 3 ml glass cartridges explained: the 300-unit standard, seals and storage | cites | Sigma-Aldrich (Merck): Handling and Storage Guidelines for Peptides and Proteins - www.sigmaaldrich.com | Lab article (https://www.preppinpeppers.com/blogs/the-lab/3ml-glass-cartridges-explained) | https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/research-and-disease-areas/cell-and-developmental-biology-research/handling-and-storage |

## FAQ

### How many units does a 3 ml glass cartridge hold on a U-100 scale?

On the U-100 scale, where 100 units equals 1 ml, a 3 ml cartridge holds 300 units. This is derived from 300 units × 0.01 ml per unit = 3 ml.

### Are standard 3 ml cartridges compatible with multiple cartridge pens?

Yes. The outer dimensions of 3 ml cartridges are standardized across brands, so one cartridge format fits a wide range of pens—including the Gansulin metal pen—eliminating brand lock-in.

### How should sealed 3 ml glass cartridges be stored?

Store below 75°F (24°C) in a clean, dry place away from direct sunlight and heat sources. Keep cartridges in their individual pouches until needed; discard any whose pouch is torn, wet, or damaged.

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