Old hot water bottles can break and cause serious burns. So, it is advised to regularly check for signs of wear and tear and not use hot water bottles that are more than two years old.
This flower symbol, found on hot water bottles, indicates exactly when it was made.
The number in the middle is the year it was made, the flower segments represent the 12 months of the year and the dots inside those represent the number of weeks. So this hot water bottle was made in April 2021.