I got this Impact Products vent adaptor and somehow messed up and forgot to use it by the time I installed my vent. I did manage to drop it though and cracked it in one spot (see bottom right image). I glued it back together with super glue and it's just as good as new. And once the vent is placed on top of it, it will be hidden and you'll put so much Dicor around the vent to seal it to the roof that it can't be seen and impossible to leak. $30, shipping included.