A few have slightly bent frames (during shipping), most are perfect. All are near new or unused. These were originally for a slot loaded open baffle project that ended up reasonably successful but too physically large to be practical. A few were used for a short while in a ripole project that was hopeless.
Most normal folk would employ these drivers thus:
1. sealed single driver subwoofers
2. sealed isobaric subwoofers
3. sealed push-pull slot loaded (PPSL) subwoofers
4. multiple distributed subwoofers to smooth out room modes
Here's an example of how to use them:
http://www.enjoythemusic.com/diy/0512/kaboominator.htmI'llalso be at the lone star audio fest for a few hours this saturday in case that's convenient for anyone interested in these drivers
Manufacturers link / data
http://www.zalytron.com/woofers.htmlhttp://www.zalytron.com/