Phoenix AF 2X Telephoto Hi-Mag Video Converter - Supplemental telephoto lens, attaches to front of lens as a filter would. Thread is 49mm. Lens is marked 46mm but I measured the threads (48.56m). I am not sure what the 46mm refers to. This is for video or perhaps stills. Please note that the rear element protrudes, I tried attaching it to a Takumar 55mm and that protrusion prevented it being attached. Condition is excellent. Any questions, just message me. Winning bidder to add $5.00 postage. Thanks for looking and please check my other listings for more photo items.