aimrite uses rubber stoppers (a very tight fit) .there is no need to worry about the amount of water that will enter threw the fibers it will never be measurable in the tube .thats just something engineers worry about, in the world of spearguns i have never found it to be a problem they just dont spend enuff time it the water
phil
Aimrite started doubble plugging my tubes because of the depths that I dive. Using a doubble plug and some 5200 will eliminate any problems that may occur from deep diving pressure.