Breather plate with 2 cast-in pins, BMW - larger openings ►see details

This type of breather plate reduces the pressure build up in the crankcase when the pistons move down in the cylinders.
It opens sooner than the standard breather plate, but closes at the same point.
This reduction of pressure helps to prevent oil leakage via the oil seal (especially the rear crankshaft/flywheel seal)