What's that, the company infamous for being restrictive as hell in regards to usability, interoperability, repair, and even infamously went to court to defend their right to throttle their consumer's hardware capabilities to force them to upgrade isn't supporting their legacy hardware?
Apple never sold this dongle. Belkin did. The video card typically has two connectors and this allows you to use a second standard monitor, which was not common at the time.
I’m fairly certain that Apple’s dongles connect an ADC monitor to a DVI video card. The Belkin connector does the opposite. I’m not positive Apple didn’t make a similar Adapter but i know I paid more like $30 for the Belkin adapter I bought for a PowerMac G4 tower.
Fyi, this case is a bit different than other Apple issues. For one thing, the ADC port the adapter is for apparently only showed up on the G4/G5 Power Mac and G4 Cube. Secondly, the ADC connector is, on paper, superior to DVI as it can not only carry video (both digital and analog, which normally require different DVI ports), but also audio, USB and power. In reality it didn't work so well because the couldn't carry enough power to run a CRT or even the higher-ens cinema displays. This lead to Apple realizing they screwed up and discontinued it in support of an unbundled cable.