Sierra STT3231R Edge Mount 12 x 12 Electric Trim Tab Kit The Sierra Edge Mount Trim Tab feature built in electronics with position sensing and CAN communication. Constructed of 12 gauge 304 stainless steel with a high quality electro-polish finish for extreme durability in marine environments. Trim tabs make the single most important difference in the way your boat rides and performs. They are optional on some boats but should be as standard as power trim and tilt. An auto-retract feature activa