Baader reverse ring M54a x 0.75

reversing ring with continuous M54 x 0.75 male thread;
Converts an M54 x 0.75 female thread to an M54 x 0.75 male thread;
Optical length equal to zero, disappears completely between two M54 x
0,75;
internal threads and therefore cannot clamp. As soon as the
When the connection is opened, the external threaded ring is also loose;
Inside reflex-free grooved and painted dead black.