'95 318ti's use an Air Flow Meter(AFM) '96+ 318ti's use a Mass Air Flow Sensor(MAF) '95 318ti's only have a pre-cat o2 sensor, '96+ 318ti's have both pre-cat and post-cat o2 sensors. But seriously though, familiarize yourself with realoem
what year car do you have???? that is very important if you wanna buy stuff.
as for the maf, the sensor is built into the housing. everyone will always sell them together since people do not want to risk wrecking the maf sensory. i am pretty sure i have one form my 98, but i need to check.