What's wrong with plastic?! Get with the times! Plastic is glass for the 21st century!! cutting edge technology incorporating high performance refractive index in an optimally delineated high density polymer matrix. I've got one of those 3x barlows. I never bothered to put it in the focuser. It looks pretty craptacular. I don't know what the lens is but the barrel and housing are all plastic.
Depends what you need it for, Vingster. If it sits in the focuser before anything else then it just adds extra travel, it's like having an extra long focuser barrel. Between barlow and eyepiece, it increases the magnification of the barlow (typically). Between barlow and camera, it reduces FOV (increases magnification, typically).
I can't believe it, but the person that told me was adamant.
I've got one of those 3x barlows. I never bothered to put it in the focuser. It looks pretty craptacular. I don't know what the lens is but the barrel and housing are all plastic.
