Seen on eBay, a prototype of a Macintosh mouse with an angled connector.
It is a fairly standard M0100 mouse, but with a bent connector in poor condition, and a damaged cable (which explained its relatively low price for such an item, $400). The seller – That Mac Guru – explains that the documentation for the first Macintosh showed this mouse, but the connector was changed shortly before its release. On a standard mouse, the cable comes out from the center of the connector, with two screws to secure the DE-9 connector. Here, the cable exits from the side of the connector, with only one screw securing it. The seller believes the purpose was to avoid damaging the cable when the Mac was placed against a wall, which seems logical.
A standard mouse
