The Nikon TC-301 Teleconverter is an updated Ai-S type of lens coupling system at its rear section. It shares similar basic specification and multiply the primary lens's focal length by a factor of 2X. While on the other hand, they decrease the effective aperture of the primary lens by two f-stops. The TC-301 is for use with a different group of lenses - those with recessed rear elements such as those lenses with longer focal lengths. The TC-301 is meant strictly for lenses above 300mm.
The TC-301 has long been famed for its exceptional optical and superb built quality. Although great attention were given to ensure it can optimize the optical excellence of the primary lens in use, but depends on combinations of variable factors, they may also have some inherent limitations too.
Dimensions: 64.5mm dia. x 115mm long (overall); 83mm extension from lens flange
This is a USED TC from Nikon, the outside shows signs of wear and age, glass has some edge marks but nothing that would effect the use.