Today I visited post office to find out more about how to post items and saw the 3 different size of Pos Express envelope, 1 Pos Daftar envelope and 3 different type of boxes pasted on the wall.

Saw the different pricing for each of it but can't remember well. Only remember the pricing for the yellow color envelope which is RM2.50 (small size envelope), RM3.00 (about A3 size), and RM4.00 (about A4 size) and red color envelope (Pos Daftar) for RM2.00

I ask the different between the Pos Express and Pos Daftar but I forgot to ask the counter what is the use of the box 
In my assumption, I thought those price (RM2.00 to RM3.80) is for the box only (not including postage cost, unlike those yellow envelope)

But I saw in this reply in this thread
Can someone enlighten me? 

if i want to send something like cable, how do i send it?
balut with the yellow paper like a worm shape?
can some1 enlighten me?