The CA1-B0-34-640-321-I is a single-pole hydraulic-magnetic circuit breaker designed for compact, high-performance overcurrent protection in industrial and commercial applications. It features a 40 A current rating with series trip (current) circuit configuration and a two-color visi-rocker actuator with vertical legend indicating OFF position. The breaker employs a unique arc chute design enabling high interrupting capacity and is rated for voltages up to 480 VAC/277 VAC at 50/60 Hz. It is available with standard rocker bezel mounting and 6-32 x 0.195 inch screw terminals, suitable for panel cutout installation. This breaker is ideal for marine, industrial automation, renewable energy, and commercial food equipment applications requiring reliable, compact overcurrent protection.