This is a Helios-44M 58mm F2.0 lens originally sold for Zenit (Zenith) cameras, with an M42 (Pentax / Praktica / Zenith) mount. Focusing is manual; aperture control is automatic using the rear pin method, with a manual override switch. It has a rear cap, its original front cap, a UV 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.

There are reviews here:
https://jonasraskphotography.com/2013/05/17/helios-44m-4-58mm-f2-review/
https://www.pentaxforums.com/userreviews/helios-44m-58mm-f2.html
These reviews cover several different versions of this lens - this one has a stop-down switch and eight aperture blades.

Condition is cosmetically and mechanically good, but there are two small black blobs in the inner elements that may be fungus or possibly paint chips, but don't seem to be affecting results. 

I tested this on a bright but overcast evening using a Canon Eos 400D with M42 screw adapter. The church was 230 yards away 1/500th f8, the tree about 30 yards 1/640th f8, the coin and stone about 7ft 1/640th f8, flowers 20 yards 1/160th f8, the coin about 18" 1/640th F8

These are highly-regarded lenses and generally sell at £25 or more, but as always I'm starting low and with no reserve.

I'm separately selling some other photographic items. If you buy multiple auction 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, about 400g; if it turns out to be cheaper than expected I will refund the balance.