It wound up that I had two separate dealers get me a pan magnet for my '98 C230 transmission.

One magnet is part# 220-271-00-98 and is a 2mm thin 40mm square slotted design.
The other magnet part# A 169 371 00 03 is a 44mm round 6mm thick magnet with a hole in the middle and it seems more powerful than the other.

I already placed the first magnet in my trans pan, but was curious why two different style/strength magnets?