I have been using a Wilderness Instructor Belt by Giles Stock. It is 1.75" wide and about 1/8" thick. It is made from MilSpec nylon webbing with either 3 or 5 lines of reinforcement stitching for rigidity. They go for about 35$. I have been wearing this 3 stitch belt for almost five years now. I even wear it with my tuxedo, under my cummerbund. I have worn it with a suit, as the jacket covers the buckle (which is flat black). I don't often wear a suit, or a tuxedo for that matter, but when I do my holster stays put.
Did I mention I had to have the beltloops on my dress slacks altered as they were too narrow? I still spent less, on the belt and alterations, than I would have for some of the leather belts that are on the market.
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Guns cause crime like spoons cause Rosie O'Donnell to be fat!