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.

Shirts

For the Bodybuilders:

For the Mass Monsters:

 Jerseys

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.

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

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