wow !! how true, caves4me !! well, today I was reading the last few pages in Deco Procedures, and the V-Planner software discussion, in that TDI book. interesting. anyway, my mind is NOT set on the hollis and the dual transmitters. just that my needs maybe more in line with the transmitter, so that I can also add the deco bottle into the equation. and yes, caves4me, there have been stories of faulty/broken by hitting transmitters.