Pearl USB-A to USB-BHARD CELL FOAM INSULATION Hard Cell Foam (HCF) Insulation ensures critical signal pair geometry. Any solid material adjacent to a conductor is actually part of an imperfect circuit. Wire insulation and circuit board materials all absorb energy. Some of this energy is stored and then released as distortion. Hard Cell Foam Insulation is similar to the Foamed PE used in our more affordable Bridges & Falls cables, and is nitrogen injected to create air