Tester Zero is almost entirely grey, symbolizing that it is the most basic of all of Vexen's weapons through the use of achromatic colors. It is shaped like an upside-down heart with one circular section taken out of each side. This has the effect of making the top of the shield resemble a spike from the Nobody logo. The shield also has two more large spikes at the bottom; one protruding from each of the bumps on the heart. Tester Zero's border is silver and its face is grey.
Tester Zero is a term usually referring to the first product being tested.
Tester Zero's ground combo begins with a simple swipe of the shield. It is followed by a sharp jab into the opponent, then finished with a sharp thrust forward.
The aerial combo begins—with Vexen jumping upwards—with a blunt thrust downward, followed by a sideways sweep, and finished with the shield spinning around Vexen, coming to rest on front of him.
|Tester Zero | Product One | Deep Freeze | Cryolite Shield | False Theory | Glacier | Absolute Zero | Gunz | Mindel | Snowslide | Iceberg | Inquisition | Scrutiny | Empiricism | Edification | Contrivance | Würm | Subzero | Cold Blood | Diamond Shield | Aegis | Frozen Pride | Pot Lid | Snowman|
| Malice | Stand-Alone | Zephyr | Tester Zero | Reticence | Black Primer | New Moon | Ashes | Basic Model | The Fool | Fickle Erica | Trancheuse | Kingdom Key|
Soul Eater | Mage's Staff | Knight's Shield | Kingdom Key D