Items sent to the South Island are done so by economy. This usually takes at least 2 days.
You can choose to upgrade to airfreight which should be overnight to urban locations.
The weights are the greater of volumetric and dead weight. eg something that is the size of a 10L bucket is 5kg volumetric weight, something the size of a 20L bucket is 10kg volumetric weight, even though the actual weight is much less. Email us on firstname.lastname@example.org to find out what weight upgrade you will need to buy.