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Wonder Looper 409gsm Double Heavyweight L/S T-Shirt is a substantial long sleeve crew neck built around one of the heaviest jersey fabrics ever produced. At approximately twice the weight of a conventional heavyweight jersey, it has a dense, structured feel while keeping a clean modern athletic fit.
Circular knit in Japan from 100% cotton, the 409gsm jersey has an uneven surface texture that gives the fabric depth and character. The construction is finished with a binder neck ribbed collar, union special flat side seams and ribbed sleeve openings, reflecting Wonder Looper’s focus on heavyweight Japanese fabric and considered garment making.
Key details
Modern athletic fit
100% cotton
409gsm / 12.1oz per square yard
Japanese fabric
Circular knit in Japan
Uneven surface texture
Binder neck ribbed collar
Union special flat side seam construction
Ribbed sleeve openings
Made in Japan
UK Standard Delivery
2-3 working days
Royal Mail Tracked 48
Free over £100
£3.99 under £100
UK Faster Delivery
1-2 working days
Royal Mail Tracked 24
£4.99
UK Next Day Delivery
Next working day
DPD Next Day
£6.99
International Delivery
Taxes & duties paid
DPD
Calculated
at checkout
Next day delivery not available to some postcodes
Next day delivery excludes bank holidays
If you wish to return your order, we offer a full refund, exchange or store credit if returned within 30 days in brand new, resaleable condition (including all tags and product packaging). We provide the returns label. International returns will need to be posted at your own expense.
Read our full returns policy.
Wonder Looper was founded in Yokohama, Japan by Bahzad Trinos and Risa Saito. The brand quickly gained recognition for their distinctive approach to fabric development after producing their 'Double Heavyweight' t-shirts (double the weight of a standard heavyweight t shirt), and the double heavyweight french terry fabric - creating the heaviest knitwear on the market. Using traditional Japanese knitting techniques, including rare loopwheel and low-tension knitting methods, Wonder Looper produces knitwear with exceptional density, softness and durability. Their garments are designed to feel substantial yet comfortable, with fabrics that develop character through wear while maintaining their structure over time.
What sets Wonder Looper apart is its constant experimentation with unusual fabrics, dyes and knitting techniques. Beyond classic heavyweight cotton jerseys, the brand explores rare textures, innovative yarns and specialised knit structures to create garments that feel distinctive both visually and physically. Every piece reflects an obsessive attention to fabric, construction and long-term wearability, balancing vintage-inspired manufacturing with a contemporary Japanese perspective.
At its core, Wonder Looper represents a commitment to elevating everyday knitwear. Rather than focusing on trends or fast production, the brand embraces slower manufacturing, traditional craftsmanship and carefully developed fabrics that stand apart from mass-produced basics. Wonder Looper creates garments built around texture, substance and the enduring appeal of Japanese-made quality.