Apple products use fasteners available from most fastener suppliers. Some local hardware stores may not carry the metric sizes widely used in Apple equipment since the introduction of the original Macintosh in 1984. If your local hardware store does not carry the fasteners used in Apple equipment, you may want to contact specialty fastener suppliers in your area. Generally, a local fastener supplier will have the fastest shipping, or may offer will call (pick up of an order).
Two locations that carry many types of fasteners, both standard heads and specialty heads such as Tamper-proof, Countersunk, Richardson, and others are: