Siegecrafting - Diminutive Siege Ram Apparatus

I was in Molvik earlier today for the 20-24 bg. So you can buy premade siege equipment at the portal keep inside of battlegrounds. It typically costs between 30 to 40 gold for already built siege equipment and all you have to do is place it near a keep or tower to do so. An ironwood siege ram from the vendor costs 40 gold, 80 silver, 45 copper. If you build an ironwood siege ram with siege craft, it is much cheaper. However, instead of the siege ram, it gives you an Ironwood Siege Ram Apparatus. If you try to use it,, all it says is, "You attempt to use the Ironwood Siege Ram Apparatus". When you click info on the item, all it tells you is who it is made by. I can not figure out how to use the siege ram apparatus or what to do with it but I would prefer not to have to spend 40 gold to buy already prebuilt siege equipment from the vendor. If you know how to get this to work, I would greatly appreciate it.