Back when Ethernet transceivers were not on board…
This is model M0437 it was the best way to connect your Mac to a network.
Let’s look at the specs:
CONNECTORS: Apple Ethernet 14-pin, RJ-45 receptacle 3 meter RJ-45 patch cable included
WIRING: Unshielded twisted-pair (telephone style)
MAX. CABLE LENGTH: 100 meters
SIGNALING STANDARD: IEEE/ISO 802.3 10Base-T
SIGNALING SPEED: 10Mbps
NETWORK STATUS: LEDs indicate link integrity and data activity
SELF-CORRECTION: Automatic correction of receive wiring polarity errors
Compatible with any Macintosh with a AAUI Ethernet port
Wow! Such technology! Such Connectivity!