The store that sold me my P01 had no holsters, so a quick trip to my favorite gun store netted me a very comfortable DeSantis "Cozy Partner" model 028 to fit a Sig 226. (The holster is labeled "028 M9") The fit, holding power and protection for the gun is excellent. This is a closed end, inside the belt, adjustable pinch, leather holster that is extremely comfortable and very well made.http://www.desantisholster.com/028.html
My only complaint about the design is the DeSantis method of belt retention involves 2 leather straps, rather than the more common metal clip. These loose straps go under the belt (at the same time you are sliding the holster inside the rear of your pants), then the loops fold around the outside of the belt and snap back at the top. It is very hard to install without almost getting dressed with the holster. So much so that for a quick 45 min walk with my wife I usually use another holster. However, for any wear longer than 2 hours the comfort is well worth it.
This is definitely all-day on-duty cop gear, not casual wear.
In finding this holster the clerk and I went through maybe 30 holsters. On form-fitting holsters we noted that you must only consider holsters for full rail, mid-sized, auto-loaders. The Sig 226 and Glock slide release levers are flush stampings, so their kydex types won't work with the P01's protruding slide release, but some leather holsters for the 226 will. You simply have to try.