The 1N6002C: Nominal Zener voltage of 12 V at 500 mW maximum power dissipation — the diode regulates or clamps at 12 V as long as the junction temperature stays within the -65°C to 175°C operating range. Maximum Zener impedance of 22 Ohms (Zzt) means the regulation voltage shifts less than 22 mV per mA of current change through the breakdown region, which is tight enough for a basic reference or a protection clamp on a 12 V rail. Reverse leakage is only 100 nA at 9.1 V reverse voltage — the diode stays off until it hits the breakdown knee, so it won't drain a bias network in a high-impedance circuit.
DO-35 axial — bench-friendly package
Through-hole DO-35 (DO-204AH) axial package — the glass body and wire leads are easy to hand-solder into a prototype board or to swap on a repair bench when the scorch mark tells you the old Zener gave up. Supplied in Bulk (tube or bag), not tape-and-reel — typical for through-hole diodes that are hand-placed or machine-inserted with radial feeders.
Tolerance and forward drop — the fine print
±2% tolerance on the nominal 12 V Zener voltage — tighter than the common 5% grade, so this part suits a voltage reference where the rail must stay within 240 mV of 12 V over temperature and current. Maximum forward voltage is 1.1 V at 200 mA forward current — if the diode is ever forward-biased in the circuit (e.g., reverse-polarity protection), budget that drop into the loop.