Plasmamen belt tank volume is 24, the extended engineering one is 6 and the emergency internals are 3.
The issue balance wise is that all of those have the same pocket size and can be printed at the same Research tier, this results on smart atmos/engineers printing a plasmamen belt tank and filling it with O2 so their internals can last for almost 2 hours instead of the 24 minutes of the extended O2.
Now they have the same volume but plasmamen lungs were rebalanced to consume plasma at a lower rate. To be clear, it will have no effect on how long the internal last for a plasmamen.
Removes a no skill trick that gives you internals that will last for all shift, you can still make those but it will take a tiny bit of effort now.
Also a small step to make internals balanced.