Early Sigma 600mm f/8 mirror lens in Olympus mount with factory lens caps and case. The focusing barrel turns smoothly and works correctly. The filter tray is in good shape. This is the early lens (the one you want) with the chrome metal handle for the filter tray and the 84mm filter ring. The later versions have a plastic handle and are 86mm and are not as good.

The lens is clean, still has its inspection sticker, with no fungus or haze that I can see in it. These are reasonably sharp lenses with good build quality. Do you need a compact long lens for your OM? This is the one for you.