How to use iframe for item's description?

[rebbeke123456789]

Hi,

I'm trying to add a description to an item but I am trying to do it using html iframe which leads to my site. However, once I put the code in it says I'm not allowed to use iframe, however I'm looking at another person's listing and they use iframe as well (http://www.ebay.com/itm/ASICS-Tiger-Unisex-GEL-Lyte-V-Shoes-H52VQ/112026962536?hash=item1a1553ca68&_...). How come that seller can use iframe however I cannot?

<iframe width="99%" height="2850" title="Seller's description of item" id="desc_ifr" src="http://bloomingdresses.com/product/off-white-black-top" frameborder="0" marginwidth="0" marginheight="0"></iframe>

Thanks