Both filters are held with the same bracket. The replaceable canister filter that resembles an oil filter is the main filter, and the prefilter (shown in the photo above) is hiding under a connection to the left of the main filter. Make sure to order both the prefilter and the O ring that goes with it. The car will not start without the O ring.

For some reason they are sold separately, which is crazy.

Rgds,
Chris W.
'95 E300D, 345K

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Objects in closer are mirror than they appear.