Iron Heart 14oz Ultra Heavy Flannel Check Work Shirt (Navy X Black)

Fans of heavyweight flannels, this is for you!

Whether worn as a jacket or under shirt, you can easily match this one up with your other gears for a quality look.

Made with a hard to find ‘Aspero’ cotton using vintage machines, the classic check pattern is woven super slowly into an amazing 14oz ultra heavy flannel fabric.

Both sides of the fabric have been carefully brushed for a soft and comfy feeling against the skin.

With time, the overdyed black colour will slowly fade to a lighter shade with some soft contrast.

As you’d expect from the makers of classic 21oz denims, this flannel is skilfully built with vintage machines and extra heavy threads.

Enjoy it with time!

  • 100% Cotton
  • Japanese 14oz ultra heavy flannel
  • Colours are over-dyed
  • Twin chest pockets
  • Urea buttons
  • Brushed interior
  • Once washed (minimal shrinkage)
  • Slim fit
  • Made In Japan

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How We Measure

Pants and Shorts


With the major buttoned up open the jeans and lay them flat like shown. Measure from the front where the major button closes to the back belt loop. Then double this measurement to achieve the waist measurement.

The way we measure is different from 'Side to Side', If you are not used to our method you should downsize by 1 inch.

For example, side to side measurement for The Flat Head 3002 waist is 28inch and using our method 29.25 inch.

Front Rise:

With the jeans lying flat measure from the crotch bar tack to the top of the waistband. 

Back Rise:

Spread out the crotch so the bar tack is visible, then measure from the crotch to the top of the waistband.


One inch down from the crotch measure flat across to the other side.


Flatten the leg and measure along the inseam from the crotch to the leg hem. 

Leg Openning:

Measure straight across the hem from side to side.



Lay flat then measure from the shoulder's edge to the other shoulder's edge.


Lay shirt flat and measure from pit to pit.

Sleeve length:

With the sleeve flat measure from the shoulder to the cuff.

Arm hole openning:

Measure from the shoulder down to the pitt.

Vertical length:

With the shirt facing down, Measure from below the collar to the bottom hem.