Mercury - Active Trim Kit (Without Trim Pad) Mechanical MerCruiser Single Engine 8M0129457. Overview. The Mercury Active Trim Kit (8M0129457) automatically adjusts your trim angle through your VesselView display, removing the need for a physical trim pad. Designed for single-engine mechanical MerCruiser 4.5L and 6.2L sterndrives (300-350 HP), it continuously monitors RPM and boat speed to deliver smoother acceleration, quicker planing, and improved fuel efficiency.. All functions are managed dir