You are bidding on a Vintage Brass Engine Oil Level Sight Glass, This was out in my 94 year old Grandfathers barn in a box marked Hit / Miss Engines, It has never been used or mounted It is 3 1/8 th in. total length It has  1/8th or 3/8th pipe thread so you can take your pick. Great patina threads are good no cracks in the glass . I have more Thanks for bidding.