TetherBoost Pro Black. Streamlined TetherBoost Pro. TetherBoost Pro is a streamlined solution to common USB 3.0 tether connection challenges, ensuring a consistent, reliable and fast USB 3.0 connection, for distances up to 65 feet, between DSLRs, Mirrorless or Digital Backs and a computer. TrueConnect LED indicator confirms the controllers stable connection, and can be used with USB base and/or extension cables. The included USB DC cable is optional for adding a USB battery (sold separately) or