Polythene Mailers - Grey 250G
No.4 Grey Opaque Poly Mailers — Secure, Professional Postal Packaging
These grey opaque polythene mailers are designed for sending non-fragile items safely and discreetly through the post or courier networks. The opaque grey film helps conceal the contents for privacy, while the lightweight polythene construction keeps postage weight down compared with boxes. This listing covers the No.4 format (previously referenced as 20G04) within Sapphire’s grey poly mailer range.
Poly mailers are a popular choice for eCommerce fulfilment because they are quick to pack, space-efficient to store, and provide a clean, professional presentation on arrival. They are commonly used for clothing, soft goods, and other items that do not require rigid protection.
Key Features
- Opaque grey film for discretion — Helps prevent the contents being seen in transit, supporting privacy and reducing the temptation for tampering.
- Lightweight mailing solution — Polythene packaging adds minimal weight, helping to control shipping costs compared with heavier outer packaging.
- Everyday durability — Suitable for typical postal handling, protecting items from scuffs and light moisture exposure during transit.
- Fast packing workflow — Simple “insert and seal” style packaging supports efficient dispatch operations.
- Clean, professional appearance — A consistent grey finish gives parcels a tidy look for customer deliveries.
Typical Uses
- Clothing and fashion items (t-shirts, hoodies, trousers, dresses)
- Soft accessories (scarves, hats, fabric items)
- Non-fragile eCommerce orders where a box is not required
- Returns packaging for apparel and soft goods
- Documents or printed materials when paired with an internal stiffener (where appropriate)
No.4 Grey Opaque Poly Mailers — Full Product Guide
Choosing the right mailer is about balancing protection, presentation, packing speed, and cost. The No.4 grey opaque poly mailer format is intended for medium-to-larger soft goods and similar items that benefit from a flexible, lightweight outer wrap. Below is a practical guide to help you decide if this style of mailer is right for your operation and how to get the best results in day-to-day use.
How It Works
A poly mailer is a flexible polythene envelope used as an outer shipping pack. You place the product inside, remove the release liner (where applicable), and seal the closure flap to create a tamper-evident parcel. The sealed mailer forms a protective barrier around the contents, helping to keep items together and shielded from handling marks and light moisture during transit.
For best results, match the mailer size to your packed item so there is enough room to insert the product comfortably without overstressing seams, while still keeping the parcel neat and compact.
Materials and Construction
These mailers are made from polythene film in an opaque grey finish. Polythene is widely used for mailing bags because it is lightweight, flexible, and resistant to tearing under normal handling. The opaque pigmentation helps block visibility of the contents, which is particularly useful for consumer deliveries.
The thickness for this product is specified as 55 microns. Thickness is one of the key indicators of how a mailer will perform in real-world packing and transit: thicker films generally feel more robust and can better resist punctures and stretching. The 55 micron specification is a common choice for general-purpose eCommerce mailing where a balance of strength and cost is required.
Note: Poly mailers are designed for non-fragile items. If you are shipping breakables, consider using protective void fill and a rigid outer carton instead.
Floor Type Compatibility (Warehouse & Packing Areas)
Because poly mailers are lightweight and flexible, they work well across most packing environments:
- Bench packing stations — Easy to store in stacks and dispense quickly.
- Pick/pack lines — Supports fast insertion and sealing for higher throughput.
- Mezzanine or compact storage — Takes up less space than boxes, helping keep packing areas organised.
If your operation uses automated label applicators or conveyor systems, ensure the sealed flap is firmly pressed down and labels are applied to a clean, dry surface for best adhesion.
Health and Safety
As with all plastic packaging, keep poly mailers away from babies and young children due to suffocation risk. In a warehouse setting, store mailers in a stable stack to prevent slips or trips, and keep packing benches clear of loose film or release liners.
When sealing, apply firm, even pressure along the closure area to reduce the chance of edges lifting during transit. If you are packing dusty items or working in a dusty environment, wipe the sealing area to help ensure a reliable bond.
Ideal Applications and Use Cases
Grey opaque poly mailers are especially well suited to:
- Fashion and apparel fulfilment — A discreet outer pack that protects garments from handling marks.
- Subscription and repeat-order businesses — Consistent presentation and quick packing for regular dispatch cycles.
- Returns programmes — Lightweight packaging that can be included in outbound orders for easy returns (where your process requires it).
- Multi-item soft goods orders — Flexible capacity for combining items without needing multiple box sizes.
If you need additional internal protection, you can pair the mailer with tissue, a poly bag, or a paper wrap around the product. For items that must not bend, add an internal stiffener or use a rigid mailer/box.
Maintenance, Cleaning and Care
Poly mailers require minimal maintenance, but good storage practices help maintain packing efficiency:
- Keep dry and clean — Store away from moisture, dust, and direct contamination so seals and labels perform reliably.
- Avoid heat and direct sunlight — Excessive heat can soften adhesives and may affect film performance over time.
- Rotate stock — Use older cartons first to keep packaging in best condition.
For best sealing performance, ensure hands and work surfaces are clean and dry, and press the flap down firmly along the full width.
Case Study (Example Workflow)
Scenario: An online clothing retailer dispatches daily orders containing folded garments. They need packaging that is quick to use, keeps parcels lightweight, and provides a discreet appearance for doorstep deliveries.
Approach: The packer folds garments into a neat bundle, adds a packing slip, and inserts the order into a grey opaque poly mailer. The flap is sealed with firm pressure, then the shipping label is applied to the front face.
Outcome: Packing time is reduced compared with building cartons, storage space is improved due to compact cartons of mailers, and customers receive parcels with a consistent, professional look.
Who Is It For?
- eCommerce businesses shipping non-fragile items
- Retailers and marketplaces dispatching apparel and soft goods
- Warehouses seeking a fast, space-efficient packing option
- Operations that value discreet packaging for customer privacy
Colours / Features Available
This product sits within Sapphire’s grey polythene mailer range. The grey opaque finish is chosen for discretion and a clean, uniform presentation. If you require alternative colours or styles (for example, different finishes or other mailing bag types), browse the wider mailing bag categories to match your packing requirements.
Sizes Available
Sapphire’s grey poly mailers are typically offered in multiple sizes to suit different order profiles. This listing relates to the No.4 format (also referenced as 16 x 21 + 2 and 400 x 525 + 50mm in the product title). If you are unsure which size is best, consider the dimensions of your packed item (including any internal wrapping) and choose a mailer that allows comfortable insertion while keeping the parcel tidy.
If you regularly ship a wide variety of order sizes, it can be helpful to stock two or three mailer sizes and standardise packing rules (e.g., “small apparel orders use size A; multi-item orders use size B”).
Ordering Notes
- Previously 20G04 — This product title indicates an earlier reference code; use the current listing for ordering.
- Pack quantities — Select the variant/pack size that best matches your dispatch volume.
- VAT — Pricing may be shown excluding VAT depending on your account and checkout settings.
If you need help choosing the right mailer for your products, consider the item type (fragile vs non-fragile), whether you need opacity for privacy, and whether you require additional internal protection for corners or edges.