Vials and pens: what the label should tell you.
Compare product identity and documentation across formats without assuming they are interchangeable.
A vial and a pen can present the same named material in very different ways. The printed name and milligram figure are only the starting points for a research assessment. Check whether the item is a dry material, a prepared solution or a filled device, and request the specification for that exact format.
For a vial
Confirm the material name, total content, batch number, container size, excipients if any, storage conditions and the tests performed on the supplied material. Do not infer the contents from a product photograph; images on a catalogue are a visual reference.
For a pen
Confirm the actual formulation, total content, concentration, fill volume, device specification and batch traceability. A pen-shaped format can imply administration, so a research-use statement should never be treated as permission for personal or clinical use.
Compare like with like
A vial price and pen price may refer to different quantities or preparations. Check the underlying specification before comparing prices. Check the current formulation, availability and batch records before ordering.