Sigma Achromatic Close-up attachment lens 

58mm +1.6 dioptre

Very good unmarked condition

(in worn Hoya case)

Please see photos

This is a high quality "Achromatic" lens

Achromatic means this is a high quality "doublet" lens 

I only know it is +1.6 dioptre through the very helpful chart here:

http://fuzzcraft.com/achromats.html

Any questions, please ask

If you have been, thanks for looking