Displaying Additional Image on Custom Template

I'm creating a custom template which breaks out of the usual design.

I need this design to show the first additional image that is shown, but i cant find anywhere that lists variables that are used to display this.

The main image is displayed using the following

{include file="common_templates/image.tpl" obj_id=$obj_id_prefix images=$product.main_pair object_type="product" image_width='460px' image_height='460px'}

Which part do i change in order to get it to point at the additional image?

Thanks in advance.

never mind, I've worked it out by printing all of the $product variables, then doing a foreach loop on the image_pairs

{foreach from=$product.image_pairs item=imageid}
{if $imageid.position=='0'}
{if $imageid.position=='1'}
{if $imageid.position=='2'}

Which outputs additional images in position 0 - 2