Now realise the 1000mm Nikkor received is different to the one advertised … I copied the dealer's original photo before ordering . The lens received does not have a front element retaining ring / 'tidying' ring … so it's going back. The lens bezel might also be missing. At some stage after the dealer's sale listing photo was taken , one or more front rings has been removed . I have advised the dealer and await a reply . Not mentioning the dealer's name because their s/h wares are usually OK . Could be several reasons why the lens has a missing ring(s)