The DSI Comet-1 CubeSat Electrothermal Water Thruster

Comet-1 is a low-power, low-profile, high total impulse electrothermal micro-propulsion system that uses water as propellant. Comet-1 is CubeSat-compatible but incorporates a highly-flexible interface suitablefor a wide range of spacecraft sizes.

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Performance specifications
Thrust 3.3 mN per nozzle (multi-thruster configurations available)
Specific impulse 200 s
Minimum impulse bit 1 mNs
Total system impulse 580 Ns
Physical and electrical properties
Power supply voltage 3 V to 34 V
Power consumption 0.3 W idle, 10 W thrusting
Command and telemetry CAN, RS-485, UART, I2C, or SPI (flexible protocol and command set)
Dimensions 98.4 mm × 98.4 mm × 108 mm (CubeSat 1U compatible)
System dry mass 350 g
Propellant mass 300 g

That high mass, 670 g makes it far to heavy for the Australian planned cubesat. It’s also physically too big.
3.3 milinewtons is a tiny thrust. But specific impulse is good. So is the thrust duration of 49 hours.

cubesat dimensions are 100×100×113.5mm and 1.33kg max.

so how is it too big.