128K through Plus
Kensington System Saver Mac. Made for the Macintosh 128K, 512K, 512KE and Plus models.
Slide it onto the top of your Mac, plug the short cable into it and the long cable into an outlet. The fan draws air up through the Mac. There are two power receptacles built in, so your external hard drive and printer can all be turned on with the two easily accessible front buttons.
Available in two colors, Beige and Platinum.
Both work great. The outer sheath of the cable on the Platinum separated at the plug end.
While it may or may not sit on top of other compact Macs, they don't have the ventilation holes. Newer models also came with a built in fan.