The "annual rings" (also known as chrysanthemum discs / date discs) on the hot water bag serve two main purposes: marking the production date and providing massage and anti-slip functionality.
Ⅰ. Core: Production Date Marking (Most Important)
This is the standard date code for the country/industry, not a decoration:
- The middle number = Production year (e.g. "25" = 2025)
- The 12 outer squares = 12 months
- The dots/holes in the squares = The week number of the current month (1-4 weeks)
- Example: The "24" in the middle, with 1 dot in the February square → Production in February 2024, the 1st week
II. Practical: Massage + Anti-slip (surface raised texture)
The annual ring protrusions on the surface of many water-filled/rubber hot water bags:
- Increase friction to prevent slipping during holding
- Perform gentle massage during hot compress to relieve muscle tension
- Thickened rubber/PVC for enhanced durability and explosion resistance
III. Safety Reminder (Must Read)
- The lifespan of a hot water bag is generally 1-2 years. If it exceeds this period, it may age and leak or even explode.
- When purchasing, check the year mark first. Do not buy old inventory that is over 2 years old.
- For electric hot water bags, the date should also be checked. It is strictly prohibited to use them beyond the expiration date.
