S&W 640 DAO holsters?

[Naphtali]

Please identify Small of Back (behind the back) and inside-the-waistband holsters for 640-1 that are particularly convenient when sitting in chairs with arms. I strongly prefer belt loops rather than clips. If there is a convenient method for securing the revolver within holster - perhaps thumb snap?? - I prefer this also.

All of the Small of Back holsters I have noticed have hand that draws the revolver with its palm in - that is, in a conventional orientation, albeit behind the back. Is there any with drawing orientation with palm facing out, as would occur with a cavalry draw? I ask because Small of Back holsters appear to have exaggerated angle on belt. For convenient access while sitting in an armchair, it appears that such an angle would be much less sensitive to where along the belt it is positioned, plus being somewhat easier to draw in the restricted space caused by chair's arms. And an inside-the-waistband holster having similar exaggerated angle for conventional cross-draw in that same armchair would appear to be similarly convenient.