The "Wilderness 1-1/2 Inch 5-Stitch Instructors Belt, original model"

http://store.thewilderness.com/product_info.php?cPath=43&products_id=2007

You want the "5-Stitch" for added stiffness over the 3-Stitch, if you plan to hang a heavy gun and holster on there. They also make a plastic insert model that is even stiffer than the 5-Stitch, but I've read many think it's TOO stiff. My 5-Stitch EASILY supports a gun with no sagging, stretching or deformity. Highly recommended.

[edit]
Here's where I bought mine from: http://www.gunnersalley.com/product/WILDERNESSBELT/Wilderness_1_12_5_Stitch_Instructors_Belt.html
[/edit]