What survival item is NOT mentioned as optional in the life raft kits?

The code card is considered a crucial item in the life raft kits, primarily because it contains essential information for identification and communication. This item allows survivors to access vital resources and instructions, making it a standard necessity rather than an optional item.

In a life raft survival situation, having a means to identify oneself and communicate with rescue teams is critical. While the other items listed may provide valuable support for specific circumstances, such as purification of seawater with the reverse osmosis desalinator or protection from sun exposure with sunblock, the code card serves a fundamental role in the survival protocols established for rescue situations.

Therefore, while items like hand-generated flashlights may be considered optional for signaling, the code card is inherently vital, which is why it is not classified as an optional item in the life raft kits.