Hi MB and readers,
I see that the usual confusion has set in so here I go cutting to the bone as usual. (;->) You specifically enquired about NewTronics, makers of the Hustler brand. You're looking for the commercial version so that's about the smartest move you can make straight off the bat. As you can see, like the Station Master they're pretuned and not adjustable for the band segment in use where they naturally exhibit thier rated gain. SWR goes up and gain goes down with departure from resonance as with any antenna so bear that in mind when selecting one for the band segment of interest. If you're only interested in receiving SWR isn't a problem but gain just MIGHT be if you're picky about it, otherwise one chosen for the center of the band or closest to the segment of interest is the way to go.
For what it's worth my Amateur radio club replaced thier 70cM repeater antenna with a Hustler and it's been working fabulously for the last couple of years it's been atop hangar one at Lakehurst (NJ) Naval Air Station. Being 200' above flat terrain with nothing around for miles doesn't hurt either but I'm talking about antenna performance and durability. This baby can't be beat, the old Hustler was up there since the Hindenburg crashed. Idiots, they tried to tie up to the antenna and a spark ignited the works. Hey guys, the tether is over THERE... uh... OOPS! (Oh, the humanity!)