[roboguy #1]

Your all thinking to off. It's got to be a sealed arm, air fils inside of it like a telescoping cylinder acutally two onve its extended it will do the standard rotate on a pivot to raise and lower. I'm right I know I'm right. Also think about it this way unless the cylinder was like microscopic bore it would never have toime to extend and retract for every tetra. Once filled topped off for leaks. I'm right I know I'm right.