size parameter for the gallery shortcode
Syntax
[gallery
order="ASC| DESC - Order"
orderby="menu_order ID| ID| title| rand - Order by field"
ids="| ID - Post ID. Default: Current post ID"
itemtag="dl| tag - Item tag"
icontag="dt| tag - Icon tag"
captiontag="dd| tag - Caption tag"
columns="3| numeric - Columns"
size="thumbnail| medium| full - Thumbnail image size"
include="| id1,id2 - IDs to include"
exclude="| id1,id2 - IDs to exclude"]
