|Yes||String||The unique SKU or ID which identifies the product|
|No||String||The name of the product|
|No||Integer||The unit price of the product in cents|
|No||String||A short description of the product|
|No||Array(String)||Categories which the product belongs to|
|No||Integer||The quantity of the product in the cart|
|No||Integer||The total price of the product (price X quantity) in cents|
|No||String||The URL of the product on your site|
|No||String||The URL of an image or thumbnail of the product|
|No||Date String||A string representing the date on which the product expires.|
expiration_datefield is stored as a proper datetime and is simply used for audience segmenting and display purposes.
Any additional params will be treated as strings and added to the
metadatafield of the cart item.