Many of my hats and caps are fitted with an adjustable head fitting.
Here’s how it works:
Firstly, undo the centre back knot and separate the two pieces of elastic at the centre back of the hat.
Then put on your hat while still holding the two pieces of elastic (it may be easier to get someone else to help at this point).
Now, while the hat is on your head, tie a single knot in the elastic so that the hat fits comfortably and take the hat off without letting the knot undo.
Finally, take off the hat and secure the knot, making sure that the ends are tucked back inside the channels.
You can repeat the process whenever necessary.
Remember that your hat will mould itself to your head to fit you with more wear and will need adjusting periodically.
This cap is made from Yorkshire Tweed and is available to buy in my online shop