Answer: First it is 6 months and not 12 months to be current.

46 C.F.R. Subpart 25.30—Fire Extinguishing Equipment

(1) When the date on the inspection record tag on the extinguishers shows that 6 months have elapsed since last weight check ashore, then such extinguisher is no longer accepted as meeting required maintenance conditions until reweighed ashore and found to be in a serviceable condition and within required weight conditions.

The following is from a manufacturers article on these replacements for Halon systems: Cylinders should be securely mounted, protected from weather, mechanical damage and be accessible for inspection and removal. Each system should be inspected and components tested at least once a year by a professional service company. The operator should check the gauge every time they go into the engine compartment or at least once a month. A visual inspection should also be made to verify the wiring is intact at the bottle and that the nozzle is not damaged.

So in addition to checking the above, there should be a signed tag of inspection from a professional service company dated and current within 6 months.