I bought these from member Lostmind in March 2007. I never used them, they work perfect.
He said the 3000 was new never used, I'm not sure about the 4700, but it looks new. I have tested them and they work perfect when I plug in and let them pump from a sink.
These were very highly regarded back then, lot's of reefers with huge tanks on reefcentral used them. You can search for info, Marine Depot and other palces have spces.
Ampmaster 4700 $125
Ampmaster 3000 $115
Here is Lostmind old listing
http://www.canreef.com/vbulletin/sho...ight=ampmaster
He asked$225 for the 4700 and $200 for the 3000. I paid 400 for both, never used them ever.
Tom