SankalpA 28mm ROPP cap is an aluminium roll-on pilfer-proof closure with a 28mm shell diameter, the standard size for packaged drinking water and beverages in India. It is written as diameter by height, commonly 28/15 mm, meaning a 28mm diameter with a 15mm skirt. Other diameters and their typical heights are listed in the ROPP cap size chart. The shell is formed onto the bottle neck during capping and carries a tamper-evident pilfer-proof band.
Why 28mm is the standard for water and beverages
The 28mm neck finish is the most widely used across packaged drinking water, carbonated soft drinks, and juices in India. It gives a mouth wide enough to fill and pour easily, while staying small enough to cap at high line speeds. Because so many bottle makers produce 28mm finishes, the size has become the default for the water and beverage segment, and closures, filling equipment, and bottles are all readily available for it.
28mm ROPP cap dimensions
A 28mm ROPP cap is quoted as diameter by height in millimetres. The 28mm diameter is fixed by the bottle’s neck finish; the height depends on the neck length and the position of the tamper band. To take those readings yourself, follow how to measure bottle cap size.
| Figure | Typical value | Meaning |
|---|---|---|
| Diameter | 28 mm | Outer diameter of the shell; must match the neck finish |
| Height | 15 mm (typical) | Skirt length running down the neck |
| Format | ROPP | Threads and tamper band formed during capping |
| Material | Aluminium | Formed from a plain shell, printable outer surface |
Treat 15mm as a typical height for water and soft drinks, not a fixed rule. The same 28mm diameter can carry a shorter or taller skirt depending on the bottle, so confirm the exact height against your neck finish. Note that ROPP sizing is not the same as a GPI code such as 28-410, a difference explained in neck finish codes and cap sizes.
How the 28mm ROPP cap works
Like all ROPP closures, a 28mm cap arrives as a plain, thread-free aluminium shell, and what a ROPP cap is covers that format in full. During capping, rollers press the soft skirt against the thread profile already on the bottle neck, forming threads that match that specific neck. A second roller tucks the lower band under the locking ring on the neck, creating the tamper-evident feature. Inside the crown sits the liner, the soft disc that forms the actual seal against the bottle rim; what a cap liner is explains how that seal is made.
Because the threads are created in place, a 28mm shell has to be matched to a 28mm neck finish. A different diameter will not pick up the thread or seal correctly.
Common applications
The 28mm ROPP cap is used across the beverage segment in India, including:
- Packaged drinking water: the most common use, often at 28/15 mm with a tamper-evident band.
- Carbonated soft drinks: where the closure and liner must hold internal pressure.
- Juices and flavoured drinks: including hot-filled products that need a heat-tolerant seal.
For each of these, the liner is matched to the contents so the seal holds pressure, keeps oxygen out, and protects taste over the shelf life. The pressure figure quoted on a beverage closure is explained in what an 8 bar pressure rating means.
R Vision’s 28mm closures
R Vision manufactures two aluminium ROPP closures at 28/15 mm:
- Aqua Cap: an aluminium ROPP closure for packaged drinking water, with a TPE liner, a tamper-evident three-part break-system ring, rated to 8 bar, and suited to hot fill, cold fill, and carbonated products. It adheres to USFDA and EU standards.
- Bev Cap: an aluminium ROPP beverage closure with a PVC-free TPE liner and a pilfer-proof ring that stays attached after opening, available in Round Ring, Two Slit, and Five Slit variants, also 28/15 mm and rated to 8 bar. It adheres to USFDA and EU standards.
Both are built for the 28mm water and beverage standard, so they drop into standard 28mm neck finishes and filling lines.
Frequently asked questions
What does 28/15 mm mean on a ROPP cap?
It means a cap with a 28mm outer shell diameter and a 15mm skirt height. The 28mm diameter must match the bottle’s neck finish, and the 15mm is how far the skirt runs down the neck. This is a common specification for packaged drinking water and beverage closures in India.
What is a 28mm ROPP cap used for?
It is used mainly for packaged drinking water, carbonated soft drinks, and juices. The 28mm neck finish is the standard across the beverage segment in India because it fills and pours easily while capping fast on high-speed lines. The liner is matched to the specific product so the seal suits water, carbonation, or a hot fill.
Are all 28mm ROPP caps interchangeable?
Not automatically. Two bottles quoted at 28mm can still have slightly different neck finishes and tolerances depending on the bottle maker. A matching diameter is necessary but not sufficient, so check a 28mm closure against your specific bottle, ideally with a physical sample, before a full production run.
Can a 28mm ROPP cap hold carbonation?
Yes, when the closure and liner are rated for it. A carbonated drink pushes outward with real pressure, so the liner must hold that pressure without letting gas escape. A 28mm closure specified for carbonated use, with a suitable liner and pressure rating, seals such products reliably.
If your bottle measures wider than 28 mm, the neighbouring standard is covered in 30mm ROPP caps. More sizing guides are collected in the learn library. To see 28mm closures for water and beverages, view the Aqua Cap and Bev Cap product pages.