A good lightning storm may be fun to watch (from a distance) but the damage done by lightning can be significant.  When lightning hits, the charge is localized and seeks the path of least resistance so that it disperses as quickly as possible.  Metal is conductor.  Plastic is an insulator.  Contegra's SLX 130 and SLX 160 submersible transducer's are made of plastic (i.e. PVC and ABS).  Thus they provide additional isolation in areas afflicted by lightning strikes (e.g. Florida).  For a graphic example of lightning prone areas around the USA, refer to the  > Lightning Density Map <