of substrate 14 are secured to a rectangularly shaped frame 22 such that the entire plate 12 and frame 22 can be handled as a unit viewing the substrates 14 from the section it can be seen that each end of substrates 14 have a greater width that the adjacent portion thereof and fits within a complimentary channels of the frame 22 located along the midpoint thereof additionally the frame has a cross sectional width greater than that of substrates 14 such that when the frames 22 and accompanying plates 12 are stacked and alternated with separators 20 slightly under pressure each frame 22 is in a closely abutting relationship with an adjacent frame and encloses the plates 12 within the grid and active material terminates short of each end of the substrate providing a space 23 defined by the interior wall 22a of frame 22 separator 20 and substrate 14 each frame 22 may be formed with a pair of spaced surface grooves 25a 27a in each major surface of frame 22 extending from the top of frame 22 terminating into channels 25b 27b channel 27b as shown in fig2 extends the entire length of frame 22 when frames 22 are stacked the grooves and channels on the abutting frame surfaces mate to form internal passageways extending from the mouth thereof to space 23 as may be seen in fig2 channel 25b communicates with space 23 near the top of frame 22 while channel 27b communicates with space 23 near the bottom thereof there are various ways to fit substrates 14 to frame 22 frame 22 may be formed.