If the items are sealed and the contents cannot be easily examined, the letter rate is applicable. Items which are not letters can be sent as parcels. Examples are machine parts, samples, goods and merchandise. In general, parels up to 20 kg are acceptable. Strong, rigid containers are recommended to better protect fragile items.
Containers are to be sealed with strong adhesive or packing tape and tied with string.
The postage can be found in the postage rate table. Some items other than letters, can be posted as small packets. For local posting, small packets are items weighing up to 500gm. The postage for small packets can be found in the rate table. Well, just about anything.