Complete with Lock nut + Rubber o'ring. Loose head for easier cleaning base of cell without twisting the leads. Replaces old cell with no adjustments. To keep your cell in good condition and running 100%. Solid plate is easier to clean.
The calcium just falls off. Of the time compared to mesh cathode. In a cathode they last longer (as they have up to 3 times more material than mesh).
There is no problem with using them in place of a mesh cell. The cell will be replaced in the first 2 years if any manufacture defects are visible.