[Shamun]

Products.tpl (Category):

  {if $config.Appearance.products_per_row && ($featured eq "Y" || $config.Appearance.featured_only_multicolumn eq "N")}

    {include file="customer/main/products_t.tpl"}

  {else}

Products_t.tpl:

              <div class="image">
                <a href="product.php?productid={$product.productid}&amp;cat={$cat}&amp;page={$navigation_page}">{include file="product_thumbnail.tpl" productid=$product.productid image_x=$product.tmbn_x image_y=$product.tmbn_y product=$product.product tmbn_url=$product.tmbn_url}</a>

                {if $active_modules.Special_Offers ne "" && $product.have_offers}
                  {include file="modules/Special_Offers/customer/product_offer_thumb.tpl"}
                {/if}
{* <a href="product.php?productid={$product.productid}&amp;cat={$cat}&amp;page={$navigation_page}" class="see-details">{$lng.lbl_see_details}</a> *}

              </div>

Thats the code for thumbnails displayed on category.
products.tpl calls products_t.tpl