I hate to talk down a product ...so I won't!
Now the DSE Squealers have no adjustments, on or off. They come ready to run on 4 AAs, (the chirppers AAAs). They run for MONTHS at a time on 4 batteries! If anything happens they fix or replace free! You do not have to mess with the sets to see if things are working.
I've caught cats at sets with both types of units but I've had nothing but grief with SOME brands and nothing but trouble free use with the DSE units. Make no mistakes they'll not make cats where there aren't none. And, if one comes and dosen't get caught things can go DEAD! Some cats won't work close enough to the squealers. I've went to putting them a ways (foot or two) back or up 3 or 4 feet in trees at my close sets...the lures will do their job. At sets where the units are tight to the trap I'll always have a cat suitable set(s) out 25 too 50 yds on the approach ways.
By the way, I have two teasre units for sale to anyone I don't really like!