The support fit well and my light sit very securely. There needed to be about a 1/8" shim placed between the bracket and the outside tank edge to reduce the down angle that it naturally wanted to sit. You should add this to the package in the future as it would be very inexpensive to make. Used 2 sided tape to attach.
Meant to order the 12", got the 8" first. This one is going to give the peace lilys and Chinese evergreen room to breathe. If there was an 18" I'd be able to set up 2 levels and be even happier. Hint hint to the vendor ;-)