A3 Wire Binding

There are 2 options to punching and binding an A3 document landscape. 

Either :-
You buy an A3 wire binder, such as the HF48, which will punch the whole length of the document in one go.
Or :-
You get an A4 wire binder with an open ended punch and selectable pins and punch one end and then the other.

To bind the document you will require 2 x A4 wires (A3 binding wires are not available) A4 wires are readily available in a variety of colours and come in boxes or 100 or 250.

The main factors in choosing the correct machine for your requirements are budget and quantity of documents to bind. 
The A4 machine will be cheaper but not as quick to use. The A3 machine more expensive but easier and quicker to use.