Don't see these too often. Like it says above 20/3.5 macrophoto lens, magnification at 10:1 with bellow or with additional extension up to 20:1. Preset and for use with Canon FD bellows or extension tubes.
The bellows adapter is removable so you could adapt it to other cameras pretty easily.
Lens shows no marks or wear and the glass looks to be perfect.
$150.00 includes shipping & insurance to US by Priority Mail, International at actual rates.