I always hand wash them in the sink. If it is wool, use a gentle detergent such as Woolite.
It may sound odd, but if it was summer I would wear the wet cap on a hot summer day and let it dry while wearing it. That helped keep its shape.
Aubreyrene has focused on top quality headwear and accessories like scarf, gloves, bags etc for over 30 years in China.
The detailed items as per below: