Transmission bands are thin steel bands that are anchored to a transmission's case and enable gear selection and action. Hydraulic transmission fluid provides the necessary force to activate these bands, which are also connected to servos. The servo mechanisms fill with the hydraulic transmission fluid in response to torque converter pressure, a process that results in the servos applying force against the bands, which then locks them into place around the transmission drums.

As all of this takes place, the flex bands allow gear action by forming a link between the transmission axle shaft and the transmission gears. Each individual transmission gear set has a corresponding set of transmission bands and drums that trigger transmission gear action. As the fluid flows out of the servos, the bands are disengaged and the entire process is reversed.

The TCI® High Performance Flex Bands feature band linings with a higher coefficient of friction for higher torque capacity and the ability to produce quicker, more positive band engagement. TCI® also carries a line of bands, referred to as "Powerbands™" that include the bullet-proof material, Kevlar. The powerbands are up to 18% wider than OE bands, providing greater torque capacity and more positive shifts and band apply. The anchor area on these bands is extra thick, heat-treated, high-carbon steel construction to eliminate the stretching and breakage often associated with stock bands. These bands are a must for any street, towing or competitive application.