Re: Sea Chest Clog Alarm
I just ordered mine from Amel, $60,62 euros each, adaptor included (ex-Vat & shipping). Hasn't arrived yet.
As far as I know, they are are made by Elettrotec – Italy (http://www.elettrotec.com/US/Vacuum_Switches.asp).
The adjustable pressure range (Elettrotec), depending on the model, is from -200 to -900 mbar.