Iron Heart Ultra Heavy Flannel Workshirt (Black X Charcoal)

Size Guide

When “The Winter Is Coming”, you know Iron Heart Ultra Heavy Flannel Workshirt is the shirt to keep your winter feel cozy!

Unlike many other brands, Iron Heart use vintage weaving machinery to achieve a detailed and strong pattern! This season they’ve remixed the classic check pattern. Thanks to the use of the black and charcoal overdyed threads, the flannel will age to soft vintage look.

Made from 100% cotton, the super soft brushed inside feels comfy to the skin and will keep you cosy. These are some of the best flannels you can get!

  • 100% Cotton
  • Japanese Ultra Heavy selvage flannel (which is slowly weaved from old machine)
  • Twin chest pocket
  • Urea "Cat's Eyes" buttons
  • The brushed interior (as comfy as some cashmere)
  • Chain-stitching construction
  • Once washed (Minimal Shrinkage)
  • Regular 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.