Battery Isolator Switch

[Nick Benson <grayoak@holly.ColoState.EDU>]

Hey all!

I just bought a switch that is operated by a plastic key.
It is designed to isolate the battery on the negative side ONLY, and will 
take 300 amps!
It was only about $9 in Wal-Mart and is made in England.  I've seen the 
fancy one in Vic. Brit catalogs, but they were nearly $50 I think.

So, my question is: Anyone mounted one of these, and if so, how well do 
they work.
I intend to install it in  my Spitfire first, and if all goes well, 
install one in my Midget.