Power/swr meter with an adjustable swr lockout feature. Can save your equipment in case something goes wrong in antenna system or if you select a wrong antenna, etc.
Where do you get that type of SWR meter? I'd love to have one of those.
MFJ (826B) have one, but the classic is probably the LP100A by telepost.
Basically they just have a PTT pass thru line, so they will unkey the amp if the antenna suddenly falls off etc.\
Very very cool, and I agree its definitely something to add to the list.