[Grant]

I first tried calling this Field internally on the customer/main/product.tpl the same way I do on the product_t.tpl but for some reason when I add this to customer/main/product.tpl it generates syntax errors.

So that's why I'm using a modded modules/extra_fileds/product.tpl instead (in case you were wondering)

This is the code I usually use which works a treat.

{assign
var="RunningTime" value=$products[product].productid|extrafield:4}
{if $RunningTime ne ""} {$RunningTime} {/if}