These chains are mandatory as per the NZ Transport Agency for use with any boat or trailer
The NZTA will refuse a WOF if your boat or trailer do not have a suitable safety chain and shackle attached.
These chains and shackles may be marked as complying with a standard and a chain designation size that equals the maximum laden weight of the trailer.
This shackle and chain are marked with a maximum laden weight of 2.5T which means that the chain is suitable for a trailer with a laden weight of up to 2500kg as the standard has already taken into account the required breaking strength