Archies Thongs are made from a specialised form of thermoplastic foam, basically, when heated to a certain temperature, the thongs will return to their original shape.
Because of these properties, it your strap has stretched, it's very easy to re-tighten your strap.
In order to re-tighten your strap, you need to apply heat to it. As such, EXTREME CAUTION must be taken not to burn yourself. So please be very careful.
Option 1 - Hot water method:
Option 2 – Hair dryer method:
*Please keep your hands away from the hot air source and be careful not to overheat your hairdryer.
Note; you normally need a fairly decent hairdryer to be able to do this.
Of course, with both methods. Please take EXTREME CAUTION not to burn yourself!
In summary, any concentrated heat source applied to the strap area will shrink the strap down and re-tighten it. Just allow to fully cool before trying it on again (NEVER try the thongs on while still hot).