I'm so stupid - for the first time in my life I was cheated by an eBay member.
The story:
My son lost my 30 years old binocular. A Russian model 7x50 with a great quality. Looking for an affordable replacement I found a good offer at eBay - a 20x50 binocular from Tasco (well known US manufacturer and now owned by bushnell). What I received was really a piece of crap. I'm pretty sure that this is a Chinese falsification. The seller rejected my complaint and said : Tasco is printed on the binocular, so what's your problem. I was relly p****d.
Therefore I contacted Tasco in US and they will investigate. Today I bought a new one from a reliable source (Celestron Skymaster 15x70)...
Thanks for reading - now I feel better!