A vest with retractable polymer spines embedded in the outer surface of the back and shoulders — the areas most commonly targeted in rear-approach assaults. When the wearer activates the system via a squeeze switch in either hand, twenty-four spines extend 3 centimeters from the vest surface. The spines are blunt-tipped polymer rods coated with a contact irritant — they do not puncture skin but deliver a sharp poking pain combined with a chemical burn sensation that makes grabbing or holding the wearer intensely unpleasant.

VoltLine designed the SB-7 to address the most common assault vector in GLMZ: the rear approach. Analysis of security footage from thousands of street assaults showed that the majority begin with a grab from behind — shoulder, collar, hood, or backpack strap. The SB-7 makes all of these grab points hazardous. The spines retract automatically when the squeeze switch is released, allowing the wearer to sit, lean against walls, and interact normally when the system is not active.

The vest is worn under an outer layer and is invisible when the spines are retracted. When extended, the spines are visible through thin outer garments but not through jackets or coats. The contact irritant coating lasts approximately ninety days before requiring reapplication — VoltLine sells recoating kits for Φ25. The vest itself costs Φ310 and is available in sizes that accommodate a range of body types.