Though no name of the manufacturer is specified, I'm pretty sure that it is LOMO objective. Though there is some chance that it is just a China clone :-) Information below is given in assumption that it is LOMO.
Special offer: if you want to test this objective and to write a review on it, please contact me - I'll give it to you free of charge (only shipping charge to be paid).
Magnification: 20x
Numeric aperture: 0.40
Iris diaphragm: No
Immersion: None
Tube: 160mm
Cover glass: 0.17mm
Focal length: 8.4mm
Working distance: 1.7mm
Parfocal height: 33mm (RMS)
Correction : Achromat
Spectrum range: 400-700nm
Research method: Darkfield
Contrast method: Phase contrast
This product was added to our catalog on Tuesday 11 April, 2006.