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 swipe from right to left. It is followed by a lunge forward, then finishes with thrusting the shield in a straight line with several hexagon shapes appearing when it comes in contact with an enemy.
The aerial combo begins with a downward slash, followed by a sweep from right to left, and finishes by sending the shield to orbit around him, causing hexagons when halted.