There is such a thing as an open carry IWB holster...but it's a bit rare for a person to use one that way. It's not that a person couldn't; it's just that they generally don't.

Concealment with an IWB holster couldn't be easier, since you only need to drape a shirt over it. So really, open carry just means making sure the shirt goes under it..

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Blog - Can You Open Carry with an IWB Holster?