A/C Belt, 5PK906, OEM - E36, E34, E39, Z3, M50, S52

The A/C drive belt runs air conditioner compressor and is driven from the crankshaft pulley on the M50, M52, S50, and S52 engines through 1998, as well as some 1999 models that still used the M52/S52, and the Z3 M Roadster/Coupe through 2000. 

Cars that used this 5PK 906mm AC Belt include: 
1992-1995 BMW 325i sedan (E36, M50 2.5 liter)
1992-1995 BMW 325is Coupe (E36, M50 2.5 liter)
1994-1995 BMW 325ic Convertible (E36, M50 2.5 liter)
1996-1998 BMW 328i sedan (E36, M52 2.8 liter)
1996-1999 BMW 328is Coupe (E36, M52 2.8 liter)
1996-1999 BMW 328ic Convertible (E36, M52 2.8 liter)
1997-1998 BMW 323is Coupe/Convertible (E36, M52 2.5 liter)
1996-1999 BMW M3 Sedan/Coupe/Convertible (E36, S52 3.2 liter)
1991-1995 BMW 525i (E34, M50 2.5 liter)
1997-1998 BMW 528i (E39, M52 2.8 liter)
1997-1998 BMW Z3 2.8 liter (M52)
1997-2000 BMW Z3 M Roadster/M Coupe (S52 3.2 liter)

It's very important not to neglect your drive belts as a failure will leave you stranded. They're easy to inspect during normal maintenance such as an oil change or refilling your washer tank. If there are cracks running across the ribs, sections missing, the edges are frayed, or the threads are visible on the belt surface, the belt should be replaced immediately.

If you can, inspect and test the A/C compressor pulley and tensioner before ordering your belt. Or plan to order these parts at the same time. These are made of plastic and shatter with age, causing potentially expansive/expensive damage to your engine, radiator, etc. They usually last longer than the belt but now is the best time to replace them. Since they are bolted on, not pressed, they are easy to replace.