Flash banner dimensions (width and height) are controlled by the banner HTML code. You can set new width and height and generate banner HTML code on your download page - please see demo here.
Default physical size of your Flash banner is 468 x 60 pixels (standard "full banner" format). You can resize your banner to some extent by changing the banner code "width" and "height" parameters expressed in pixels.
To avoid the graphics distortion, you should keep original aspect ratio between width and height. For example, for the 468 x 60 Full Banner ad format, recommended width:height value pairs are: 562:72, 608:78, 702:90, 750:96 etc. Please see tips and tricks on the banner download page for the banner HTML code examples.
The same approach should be used for Leaderboard (728 x 90), Medium Rectangle (300 x 250), Large Rectangle (336 x 280) and Wide Skyscraper (160 x 600) ad formats available through our Instant banner maker services.