This is a Sony-made lens that is equipped with a Sony E (NEX) mount. If you want to use a filter on the lens, then the filter size is 49 mm.
From Camix
Sony FE 55mm F1.8 ZA Carl Zeiss Sonnar T Lens [Brand New]
Too expensive? Get a notification as soon as the price drops.
This product is also available at 1 unverified merchant.