Remember:
I never had a bleeding

from my foreskin, even since I started doing this (see QUOTE above).
I believe that the
MgCO3 (magnesium carbonate) is acting like a protective layer between the sensitive skin on my penis, and the
THERABAND (the yellow), there is not to much slippage, and not to little slippage between the
THERABAND and the skin, the friction COEFFICIENT is just perfect.
If I compare
baby powder (body powder) TO MgCO3.
MgCO3 is the clear winner in it's ability to help with grip and friction protection on the penis skin, and therefore protect the penis skin from wear and tear.
Either if you are doing manual stretches bearhanded, or are using a device like: broomstick 1.0, Power Assist 2.0 or LengthMaster 3.0, it will protect and create a secure grip on your penis. Remember that when you get your new piece of THERABAND it has pre-applied powder on it. Personally I think for wrapping in the LengthMaster 3.0 the pre-applied powder is to much, so I always wash the theraband before usage. I'm on my second 2 pieces of THERABAND now, and I have been stretching for almost a year.
But if you combine MgCO3 and body powder the benefits of MgCO3 will disappear.
But I presume that the MOSGRIP will leave these basic powders in the dust for sure, because MOSGRIP was developed specifically for stretching the penis.
Look at this product video for MOSGRIP, do you see the insane grip between the fingers. 
Nowhere near what MgCO3 can produce.