of the elongated synthetic plate fig1 such that the two magnets have a relatively large separation between them the synthetic plate has a t shaped depression 4 and a t shaped raised area 5 at each of two corners of the plate 1 there is a small round recess 6 7 and at each of the other two corners a knob 8 9 is formed the plate is provided with a thin raised bead 10 the device according to the invention includes two synthetic plates according to fig1 which are pressed together with the magnets sandwiched between them and fused or welded with the knobs 8 9 of one plate engaged in the recesses 6 7 of the other plate after the welding of the plates provided with the two permanent magnet bars in the depressions 2 and 3 a very handy hermetically sealed flat device arises in the form of a credit card which can be thrown into a washing machine of any type with ease this increases the effectiveness of the detergent during the laundering of linens clothing etc the device according to the invention with the two built in permanent magnet bars functions as follows since the device is constructed flat in the form of a credit card and is also relatively light it moves about readily in the wash water so that eddy currents are induced in the ionized water by its motion which effects a very slight decomposition of dissolved salts and also in very small amounts of the water this reduces the effect of hardness formers such as calcium and magnesium tests have shown that the water becomes 34 softer 34 as.