Skylight - Looks like a  juicer
 
 
 
Description I purchased this on eBay as a large juicer.
Material Glass - Clear with green tinge
Diameter 153 mm
Length  
Height 125 mm
Weight Heavy
Maker One current manufacturer is Marshall Machine Works
Notes It turns out that this is a fitting for a skylight - see http://www.boatdeckprism.com http://www.glassian.org/Prism/Gallery/Deck/index.html (this site refers to it as a 'Reamer" style)
   

 

Skylight - Looks like a juicer next large glass juicer
Skylight - Looks like a juicer with ruler
Skylight - Looks like a juicer next large glass juicer
Skylight - Looks like a juicer next large glass juicer