[Amps] Machlett 3-500z

[Warren Volz]

Tonight while searching for 3-500z on eBay I discovered this listing: https://www.ebay.com/itm/222576972694 

I know all 'new' tubes are made in China and the rfparts version seems to get the best reviews. Any idea what the deal is with these Machlett 'factory direct' models? They are $90 less than rfparts. Are they the rejects from elsewhere or the manufacturer trying to undercut the market?

-Warren KD5YPH