One of the most popular postal services first class mail aims to deliver your letter or packet the next working day including saturday maximum weight 20kgs per stamp the maximum dimensions for rectangular items are 610mm x 460mm x 460mm the maximum length for rolled items is 900mm and the length plus twice the item diameter must not exceed 1040mm there is no weight limit for items sent first class you will recieve 4 booklets of 12 self adhesive first class stamps