What Rocket Am I?: Quiz 17

Clue 1: I was developed by Rocket Lab in New Zealand/USA.
Clue 2: My payload to low Earth orbit is 300 kg.
Clue 3: I launched CubeSats on "Still Testing" mission.
Clue 4: I am a small-lift reusable orbital rocket.
Clue 5: I stand 18 meters tall.
Clue 6: I use electric pump-fed engines.
Clue 7: I was first successfully launched in 2018.

Yes, I am Electron.

I pioneered mid-air booster recovery attempts with helicopters.