This original insert allowed the simple exchange of modules. It fixed the issue of every time you wanted to modify your S10 it destroyed the mask. 
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Version two takes this great concept and improves upon it. The most noticeable change is the reversal of the screw thread. When attaching the insert to the mask, the nut is screwed on anti-clockwise. This will improve the issue of when you unscrew a module it unscrews the insert instead.
 
If selected on other modules, one will be provided free of charge. However if you want any additional please add them here. 
 
Gas mask not include