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Diamond Theory Clothing

Paradox Black Paisley Mass Fit Men's Shirt

Regular price £90.00 GBP
Regular price Sale price £90.00 GBP
Sale Sold out
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The Shirt

- Obsidian Black Mass Fit Men's Shirt
- Windsor Collar
- Long Sleeve

This is a Shirt for the Pros

Introducing the epitome of next-level innovation in athletic apparel—the Diamond Theory Mass Fit Shirt. This Shirt transcends all conventions. Worn by the world's greatest professionals, this isn't just a shirt; it's a revolution in the realm of clothing for athletes.
Redefine your perception of a perfect fit. This shirt isn't merely tailored; it is crafted with a precision that transcends convention, this shirt redefines the very essence of "muscle fit.” It's not merely about snugness; it's about an artful orchestration of fabric, form, and function.

Witness your athletic shape shown to perfection as the shirt tapers and drapes in all the right places with every stitch, every contour a testament to the artistry of design, engineered to harmonise with the physique of champions.

Designed to drape elegantly over muscle bellies, this shirt is a symphony of aesthetics and comfort. The fabric gracefully follows the contours of your body, creating a silhouette that not only showcases your hard-earned gains but enhances the visual impact whilst maintaining sophistication and maturity. It's not just clothing; it's a canvas for the sculpted masterpiece that is your physique.

With a meticulously crafted taper, we've designed the waist to provide the perfect room without compromising the striking silhouette. With shoulders and chest as the focal point, every wear tells a story of power and authority. This isn't just a shirt; it's a declaration of strength and dominance, worn proudly by those who command respect and admiration in every arena.

Walk among giants, shoulders broad, chest proud, and embrace the unmatched confidence that comes from wearing a garment tailored to elevate the mightiest of figures.

Prepare for the world to take notice, for heads to turn, and for admiration to follow. This isn't just a Mass Fit Shirt; it's an experience—an embodiment of sophistication, innovation, and unparalleled style. Embrace the evolution of fit, and embrace your journey to the top with every wear.

What is My Fit?

Diamond Theory has 2 Fits for shirts:

Muscle and Mass

  • Muscle: This fit is designed with Bodybuilders in mind as this has an aggressive taper, bringing it right in at the waist.
  • Mass: This fit is designed with Strongmen in mind as this has a less aggressive taper as Strength Athletes tend to have a thicker core.

Please take this as a reference and refer to the size guide with your measurements.


Check our Size Guide. Select the shirt most accurate to your measurements.

This shirt has been engineered from the ground up specifically for real athletes who carry real muscle and mass. Designed to drape and flow like a shirt should.

Before you order, please make sure you measure yourself and choose your size according to the size guide. Take your chest measurement and your waist measurement. No need to order a size down for a tighter fit.

Suggestion: If you are at the top of a size bracket, opt for the size up.


For the Bodybuilders:

Size Guide, Muscle Fit, Muscle Fit Shirt, Muscle Size Guide



For the Mass Monsters:


Our Training Fit Size Guide:



Our shirts are made of 97% cotton and 3% elastane. Why? Simply put, because this is the best fabric blend to use. Cotton is lightweight and breathable, which means you are comfortable and don’t overheat. We use a small amount of elastane to allow for a little bit of stretch to aid comfort. We don’t use too much so the fabric remains lightweight, breathable and of the highest possible quality.

Shipping & Returns

Free Shipping over £50
For returns please see returns policy for further detail

Care Instructions

Wash on a low heat, air dry and press. Do NOT tumble dry.

  • Free Shipping over £50