Tom Walker played a large part in the design of the bass preamp. They were the first production guitar and basses to use active electronics which could boost levels in selected frequency bands. The preamps were coated with epoxy to prevent reverse engineering. The StingRay Bass sold well. While highly innovative electronically, the guitar was not blessed cosmetically and met with little success. In December 1978, a two-pickup bass was introduced called the Sabre (discontinued in 1991). A redesigned guitar bearing the same name followed. Both sold poorly.