The 8" cable has a 1/4" female connector and a 1/8" male connector.
Grado offers a mini adaptor cable that converts a 1/4 inch (6.3mm) plug to 1/8 inch (3.5mm) plug. The mini adaptor cable has a 1/8 inch (3.5mm) plug then 8 inches (20cm) of cable connected to a 1/4 inch (6.3mm) jack. The 8 inches (20cm) of cable eliminates added leverage on the output circuit board of the source. The mini adaptor cable is constructed of the same high quality wire as their headphone cable. Grado guarantees no degradation of sonic quality with Grado headphones while using their mini adaptor cable.