This is a manually-operated Helios-44-2 58mm F2.0 lens originally sold for Zenit (Zenith) cameras, with an M42 (Pentax / Praktica / Zenith) mount. Focusing and aperture control are manual. It has front and rear caps, a skylight filter and a cloth storage pouch. At 58mm it's a standard lens for a 35mm SLR, a moderate telephoto for a digital camera with an APS-C sensor. It ought to be useful for portraiture and macro work. It should fit most SLRs with an appropriate adapter mount, though some cameras (e.g. Nikon) will need a mount with a corrective lens to focus to infinity. Since the rear element protrudes slightly towards infinity these lenses may not be compatible with all adapters.

This is mechanically and cosmetically good, optically about average, with some internal dust which may be spores. There does not appear to be any fungus. The iris is slightly oily. Focusing and stop down work well, and cosmetic condition is very good apart from slight wear to paint on the edge of the aperture rings.

I tested it on a Praktica body and took test pictures on a cloudy afternoon after rain using a Canon Eos 400D with M42 screw adapter, set to ISO 800, with the iris set to f8 for all shots.
Church 230 yards 1/1600th f8
Tree 30 yards 1/250th f8
Garden (bird bath 17 yards) 1/160th
Coin and brick bits 7ft 1/250th f8
Plant on edge of roof 11ft 1/250th f8
Coin in closeup about 18" 1/8000th F8

There are reviews on these sites:
https://jonasraskphotography.com/2013/05/17/helios-44m-4-58mm-f2-review/
https://www.pentaxforums.com/userreviews/kmz-helios-44-2-58mm-f-2.html

As always I'm starting low and with no reserve. I'm separately selling some other photographic items. If you buy multiple items from me please request a combined postage invoice, I'll do my best to get it down to the lowest possible price. I do not make any profit on postage.

International buyers: The postage price shown is based on an estimate of packed weight, around 350g, if it's cheaper than expected I will refund the balance. This will be sent by a tracked postal service; if multiple items are sent (max 2kg total packed weight) the tracking applies to the whole package and works out much cheaper per item. Please note that eBay will add VAT or sales tax to the final price in the EU and some other countries.