This is the Olympus Macro 35, it is a macro lens. The lens has a 62mm threads on the camera end and 72mm on the filter end. The operating range of the Macro 35 is from 4.7 inches to 13.8 inches and unlike most of the other extension lenses, it can be used over the full range of the zoom.
The lens come in a small case with a screw on rear cover and a snap on front one.
This link will give you more info on the Macro 35
http://davidweikel.com/E10_samples/mcon35/mcon1.shtml

By Bill Huber