The venerable Bianchi Model 6 waistband holster.
For years as either law enforcement or a license holder I have carried a firearm. Sometimes for sporting reasons, perhaps on fishing trips in snakey areas, and often for safety reasons. When working plainclothes or undercover and when off-duty, I often carried a Smith and Wesson Model 38 or a Colt Cobra. That was back in the day when revolvers were still somewhat revered in law enforcement, although there was there fair share of 1911 variants, HK's, Hi-Powers and S&W autos.
But many of my collegues opted for revolvers. My duty weapon was a 4" Colt Python, too large for any type of concealed carry except in a Jackass Leather shoulder holster under a properly fitted suit coat or winter jacket.
One of the first holsters I bought for off-wear was the above holster, the Bianchi Model 6. I bought a few more off of ebay a few years ago, but still use that original holster I bought back in the early 80's. All of mine have the shiny chrome metal clip, but they're basically identical to the one shown above.
It's handy for a variety of reasons. It's nice to be able to carry your pistol in a briefcase or backpack if the situation doesn't require having a weapon directly on your person. Under such circumstances, having your pistol in a holster like the Model 6 means that you can be wearing it in just a few seconds.
I only wish they made one in some sort of forward FBI cant, as that is my favorite angle for carry of almost all type.
I tried many other and more substantial IWB holsters with very little success. Bulk is a problem with almost all of them except for suede ones like the El Paso Saddlery Summer Special and it's ilk made of thinner leather.
For what it's worth, I still use my original Model 6 nearly 30 years after it's purchase. It's in excellent shape, and it fits the pistol it's been carrying all that time like a glove.
True concealed carry of a firearm is an art and a science. While many custom holster makers have great holsters for concealment, I think I've come full circle with the Model 6. Although I've tried and bought fancier and much more expensive holsters since my original Model 6, the past few months I've been using them more frequently.
Good Job, Bianchi. Now bring back the B-LITE with some sort of cool LED lights and get back in the police flashlight business.