Speaker Accessories - Bars for Speaker Box>>>

Where could I purchase bars for my speaker box like this:
View attachment 456694

I have seen them on other people's speakers at shows, and I would like to add a coupke to my 10W7 box that I have in my trunk for show, and for safety of the woofer cone. Suggestions would be appreciated as well as how they would install.

Thanks.

~Darren