It is a Nikon AI Mount. It will mount on to any Nikon film or digital SLR body without any problems. It is also easily adaptable to Micro Four Thirds, Sony E-Mount (NEX), Canon EF (EOS), or Fuji X-Series. You will need an adapter which are very inexpensive here on eBay. This sale does not come with an adapter.

This is a constant aperture lens. So you can be at 210mm at it will still be f/3.5 unlike other lenses that go to f/5.6 at the long end. This lens is nice and sharp. It has a great metal body construction. It is built like a tank. Series 1 is the Vivitar high end lens line from back then. This lens is always highly regarded.This is a multi-coated lens. 

The glass is clean on both ends. There is no fungus or haze. The blades are oil-free. I can't see any but it looks like it is free of internal dust too. Which is rare. Lenses of this age usually get internal dust normally. 

It comes with the original front and rear lens caps. This is a push-pull zoom lens. The focus ring turns nice and smoothly and then you push or pull on the same ring to zoom in or out.