You make them.

Get some small circuit board drills and bore out some plastic rod with different diameters and put it inline in the hose.

Or, find some tubing, fill it with hot glue and use little wires and pins of varying diameter and poke holes after heating the pins with a lighter.

Be creative.

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles
97 C280 147k miles