The tension oxygen tank — this was the underwater breathing apparatus Shen Cong designed after half a day of thought.

The working principle was very simple. Using the pulling force generated by the arm and leg movements of swimming, transmitted through pull-cords and a concentric gear train, it drove pistons to perform piston motion inside two air cylinders on his back, thereby reducing the pressure within the cylinders and feeding the separated air into the interior of the Hell Plant Armor.

Shen Cong's physical qualities were already hard to reckon by now; the vague standard of bulls of force was growing ever harder to sum him up by. If one insisted on defining it, he was roughly at forty-bull quality.

A lift of the hand, a step of the foot could put out several tons of force.

Even with the heavy resistance underwater, it was still hard to constrain Shen Cong's performance, so human power could perfectly well be used to separate the air in the water and obtain oxygen.

There were two tension oxygen tanks in all, one on each side, left and right.

They were detachable equipment; when not in use, he'd take the tension oxygen tanks off, and the pull-cords on his arms and legs needn't be removed — they weren't in the way.

Very convenient to use.

"Whether the final effect works or not, that's for a water trial." Toward evening, Shen Cong fitted on the tension oxygen tanks, fully sealed the visor of his helmet, and jumped into the barrier lake.

Underwater, he immediately started swimming.

Just a touch more paddling force than before, and the pistons in the tension oxygen tanks were driven like the wind, the powerful effect beginning to depressurize and separate the air.

The separated gas, as the pistons moved on the downstroke, was pressed out from a partition and forced into the interior of the Hell Plant Armor.

After it was breathed, the waste gas was then discharged out through a breathing tube on the other side.

Run through this whole process, the interior of the Hell Plant Armor had…