When a USB link carries more than data, isolation matters. The Black Box SP387A USB isolator inserts between a PC and a USB device to block damaging electrical events and reduce ground-loop problems that can interrupt measurements or stress connected hardware. With isolation up to 4 kV, it is suited to environments where signal integrity and equipment protection are both non-negotiable. USB 1.1 compliance keeps the device aligned with legacy peripherals commonly found in lab, medical, and industrial systems. The included 1 m, 3.3 ft USB cable simplifies installation and keeps the isolator easy to place inline without reworking the workstation layout. This is not a generic accessory. It is a targeted protection layer for systems where a failed USB connection can mean lost readings, interrupted workflows, or avoidable service calls. For organizations that need to protect specialized devices rather than consumer peripherals, the SP387A offers a focused, practical answer.