All of the REAL tests of the various magical pulse desulfators including a series by our own esteemed Bill Trayfors have found the devices worthless.
Don't believe ANYONE who tells you different. If the battery cannot be revived by equalization it cannot be revived by a "desulfator".
Here's what Bill commented elsewhere:
And, after over 18 months of testing the little pulsers mentioned above (which are NOT chargers, by the way) -- including the PulseTech models, of which I own several -- I don't have much faith in their claims to work as desulfators and to restore lost capacity. We found that after over a year of "treatment" with these desulfators, and vigorous exercising of the flooded and gelled golf-cart batteries under test, very little change in capacity occured. However, the flooded batteries were equalized a couple of times, and exhibited a significant increase in capacity.