These are DIN 28 polypropylene caps designed specifically for glass syrup bottles. Available in black and white, with sizes covering the full standard range — 30 ml, 60 ml, 100 ml, 125 ml, 150 ml, 200 ml, and 250 ml — each cap includes a PE foam liner that creates a leak-resistant, tamper-evident seal. They're sold wholesale by the box and priced per unit, so you're buying exactly what your production run needs without paying for packaging you don't. Browse our glass syrup bottles to find the matching bottles, or explore the full closures collection for other closure types.
What DIN 28 Means — and Why It Matters
DIN 28 is the international standard neck finish for pharmaceutical and medical-grade syrup bottles. The "28" refers to the outer diameter of the bottle neck in millimeters, and the DIN standard specifies the thread pitch and height so caps and bottles from any manufacturer fit together consistently. It's not interchangeable with standard 28/400 closures used on food and cosmetic bottles — the thread geometry is different. So if you're packaging cough syrups, oral suspensions, herbal liquid extracts, or compounded liquid medications in glass syrup bottles, you need DIN 28-specific caps. That's what these are. Each one fits precisely, seats flush, and won't back off or leak under normal handling and shipping conditions.
Applications: Who Uses These Caps
The primary buyers for DIN 28 syrup bottle caps are companies working in pharmaceutical compounding, nutraceuticals, herbal medicine, and veterinary liquid formulations. But the use cases stretch further than that. Small-batch producers of liquid vitamins, elderberry syrups, immune supplements, and functional wellness tonics all use these same caps because the bottles — and by extension the closures — come from the pharmaceutical supply chain. The glass is inert and easy to sterilize, the DIN 28 seal holds up through hot-fill processes, and the tamper-evident ring gives end consumers a clear visual indicator that the product hasn't been opened. For any brand selling a liquid product where integrity and presentation both matter, these caps do the job cleanly.
Cap Specs at a Glance
All caps are made from polypropylene (PP), which is chemically resistant, food-grade, and compatible with a wide range of liquid formulations. The PE foam liner inside each cap compresses against the bottle neck to form a reliable liquid seal. The tamper-evident ring snaps below the bottle's bead ring on first opening — so if a cap arrives at a customer without the ring intact, they know immediately. Black caps offer a premium, clinical look that works well for branded wellness and supplement products. White caps are the standard pharmaceutical presentation and are the most widely specified in compounding and medical contexts. Both colors are available across all seven sizes.
Who This Is For
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Pharmaceutical compounders producing oral liquid medications, cough syrups, and suspensions that require standardized DIN 28 closures
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Herbal and botanical brands packaging liquid extracts, tinctures in syrup form, elderberry, echinacea, and other liquid wellness products
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Nutraceutical manufacturers bottling liquid vitamins, mineral supplements, and functional tonics
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Veterinary product producers needing leak-proof closures on oral liquid medications for animals
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Private label brands building a supplement or wellness line around glass syrup bottle packaging
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Small-batch wellness producers scaling from cottage production to retail-ready wholesale quantities
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Contract packagers and co-packers who need a reliable closure source that ships consistently and fast
Frequently Asked Questions
What bottles do these caps fit?
These caps are designed for glass syrup bottles with a DIN 28 neck finish. Each size (30 ml through 250 ml) is matched to its corresponding syrup bottle — the cap that fits the 30 ml bottle won't fit the 100 ml bottle, and so on, because the bottle body changes but the neck diameter stays the same at 28 mm. Always order the cap labeled for your bottle size. You can view matching bottles in our syrup bottle catalog.
Are these caps compatible with hot-fill processes?
Polypropylene has a heat tolerance that handles typical hot-fill temperatures. That said, compatibility depends on your specific fill temperature, dwell time, and formulation. We recommend testing caps with your product and process before committing to a full production run — standard practice for any pharmaceutical or food-grade application.
Do these caps include a liner?
Yes. Every cap in this collection includes a PE foam liner. The liner compresses against the glass bottle neck to create a liquid-tight seal. It also contributes to tamper evidence — once the cap is applied and the ring snaps, the seal is intact until the consumer opens it for the first time.
What's the minimum order?
Caps are sold by the box. Box quantities vary by size — for example, the 30 ml caps come 350 per box, while the 250 ml caps come 120 per box. There's no minimum number of boxes. Order one box to test, or multiple boxes for a full production run. Sample orders are available if you want to verify fit before committing to a larger quantity.
Are these FDA-compliant or food-grade?
The caps are made from food-grade polypropylene. For pharmaceutical or regulated nutraceutical applications, you're responsible for confirming that your complete packaging system — bottle, cap, and liner — meets the specific regulatory requirements for your product category. We supply the packaging; compliance verification for your formulation is on your end, as it should be.
How fast do orders ship?
We ship across the USA in 3–5 business days. The Bottle Depot has served 5,000+ customers since 2018, and fast, reliable fulfillment is something we take seriously. If you need to verify stock availability before placing a bulk order, reach out through our contact page.
Can I get these caps in other colors or with custom printing?
Currently these caps are available in black and white only. If you're looking to differentiate your product with custom color caps or printed closures, visit our custom printing page to discuss what's possible for your run.
