Finalized terminal spacing, basket color, venting, cast aluminum surround clamp rings, etc. After about a year of work I think the U series maybe ready to start production soon. Stay tuned for more updates! This will be our new series to bridge the gap from the SA to the X v.2 series -- it is also the most direct replacement for the discontinued Z v.3 series but at a much lower price. They use the same voice coil as the X v.2 series; therefore RMS power is 1500-watts rated conservatively. The motor is a similar design to the X v.2 series with one less magnet slug since it isn't needed for use on these frames & soft parts. It also retains a magnet ID shorting ring just like the X v.2 series motor. I have tooled 4 new cone bodies & surrounds to mate up to an entirely different frame tooling from the 1st prototypes. These surrounds are based on the Z v.3 18" surround geometry as this has been our go-to cone for SPL (we use those cones in our Terra for our World Record in SS 3-4 class). We also have tooled the cones to support the same wide-flange dust caps we use on all the new platform drivers. They also feature custom tooled cast aluminum vent spacers to mate up correctly to these frames. We tooled 2 different spacers for this line. Another new feature (also fully custom tooled) is the cast aluminum surround bolt-on ring. We tooled one for each size U series. These woofers will have a similar sound to the Z v.3 series -- meaning they do not have the "new platform" sound of the X, Z, NS, etc.